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Updated: Wednesday, February 9, 2022
 
 

fetchmail (1)

Name

fetchmail - capable server

Synopsis

fetchmail [option...] [mailserver...]
fetchmailconf

Description

fetchmail reference manual                                        fetchmail(1)



NAME
       fetchmail - fetch mail from a POP, IMAP, ETRN, or ODMR-capable server


SYNOPSIS
       fetchmail [option...] [mailserver...]
       fetchmailconf


DESCRIPTION
       fetchmail  is  a mail-retrieval and forwarding utility; it fetches mail
       from  remote  mailservers  and  forwards  it  to  your  local  (client)
       machine's  delivery  system.   You  can  then handle the retrieved mail
       using normal mail user agents such as mutt(1), elm(1) or Mail(1).   The
       fetchmail utility can be run in a daemon mode to repeatedly poll one or
       more systems at a specified interval.

       The fetchmail program can gather mail from servers  supporting  any  of
       the  common  mail-retrieval protocols: POP2 (legacy, to be removed from
       future release), POP3, IMAP2bis, IMAP4, and IMAP4rev1.  It can also use
       the ESMTP ETRN extension and ODMR.  (The RFCs describing all these pro-
       tocols are listed at the end of this manual page.)

       While fetchmail is primarily intended to be used over on-demand  TCP/IP
       links  (such  as  SLIP  or PPP connections), it may also be useful as a
       message transfer agent for sites which refuse for security  reasons  to
       permit (sender-initiated) SMTP transactions with sendmail.


   SUPPORT, TROUBLESHOOTING
       For troubleshooting, tracing and debugging, you need to increase fetch-
       mail's verbosity to actually see what happens. To do that,  please  run
       both  of  the  two  following commands, adding all of the options you'd
       normally use.


              env LC_ALL=C fetchmail -V -v --nodetach --nosyslog

              (This command line prints in English how  fetchmail  understands
              your configuration.)


              env LC_ALL=C fetchmail -vvv  --nodetach --nosyslog

              (This  command line actually runs fetchmail with verbose English
              output.)

       Also see item #G3 in fetchmail's FAQ <https://fetchmail.sourceforge.io/
       fetchmail-FAQ.html#G3>

       You  can  omit  the LC_ALL=C part above if you want output in the local
       language (if supported). However if you are posting to  mailing  lists,
       please  leave it in. The maintainers do not necessarily understand your
       language, please use English.


TLS (SSL) QUICKSTART
       Your fetchmail distribution should have come with  a  README.SSL  file,
       which  see.  It is recommended to configure all polls with --ssl --ssl-
       proto tls1.2+ if supported by the server,  which  configures  fetchmail
       along  recent  IETF  proposed  standards  and  best  current practices,
       RFC-8314, RFC-8996, RFC-8997.


CONCEPTS
       If fetchmail is used with a POP or an IMAP server (but not with ETRN or
       ODMR),  it has two fundamental modes of operation for each user account
       from which it retrieves mail: singledrop- and multidrop-mode.

       In singledrop-mode,
              fetchmail assumes that all messages in the user's account (mail-
              box)  are  intended for a single recipient.  The identity of the
              recipient will either default to the local user  currently  exe-
              cuting fetchmail, or will need to be explicitly specified in the
              configuration file.

              fetchmail uses singledrop-mode when the  fetchmailrc  configura-
              tion  contains  at  most a single local user specification for a
              given server account.

       In multidrop-mode,
              fetchmail assumes that the mail server account actually contains
              mail  intended  for  any number of different recipients.  There-
              fore, fetchmail must attempt  to  deduce  the  proper  "envelope
              recipient"  from the mail headers of each message.  In this mode
              of operation, fetchmail almost resembles a mail  transfer  agent
              (MTA).

              Note  that  neither the POP nor IMAP protocols were intended for
              use in this fashion, and hence envelope information is often not
              directly  available.   The ISP must stores the envelope informa-
              tion in some message header and. The ISP  must  also  store  one
              copy  of  the message per recipient. If either of the conditions
              is not fulfilled, this process is unreliable, because  fetchmail
              must then resort to guessing the true envelope recipient(s) of a
              message. This usually fails for mailing list messages and  Bcc:d
              mail, or mail for multiple recipients in your domain.

              fetchmail  uses  multidrop-mode  when  more  than one local user
              and/or a wildcard is specified for a particular  server  account
              in the configuration file.

       In ETRN and ODMR modes,
              these  considerations do not apply, as these protocols are based
              on SMTP, which provides explicit envelope recipient information.
              These protocols always support multiple recipients.

       As  each  message is retrieved, fetchmail normally delivers it via SMTP
       to port 25 on the machine it is running on (localhost), just as  though
       it  were being passed in over a normal TCP/IP link.  fetchmail provides
       the SMTP server with  an  envelope  recipient  derived  in  the  manner
       described  previously.   The  mail  will then be delivered according to
       your MTA's rules (the  Mail  Transfer  Agent  is  usually  sendmail(8),
       exim(8),  or  postfix(8)).   Invoking  your system's MDA (Mail Delivery
       Agent) is the duty of your MTA.  All  the  delivery-control  mechanisms
       (such as .forward files) normally available through your system MTA and
       local delivery agents will therefore be applied as usual.

       If your fetchmail  configuration  sets  a  local  MDA  (see  the  --mda
       option), it will be used directly instead of talking SMTP to port 25.

       If  the  program fetchmailconf is available, it will assist you in set-
       ting up and editing a fetchmailrc configuration.  It runs under  the  X
       window  system and requires that the language Python and the Tk toolkit
       (with Python bindings) be present on your system.   If  you  are  first
       setting  up  fetchmail for single-user mode, it is recommended that you
       use Novice mode.  Expert mode provides complete  control  of  fetchmail
       configuration,  including  the multidrop features.  In either case, the
       'Autoprobe' button will tell you the  most  capable  protocol  a  given
       mailserver  supports,  and  warn  you  of  potential problems with that
       server.


PREFACE ON THIS MANUAL
       Fetchmail's run-time strings have been translated (localized)  to  some
       languages, but the manual is only available in English.  In some situa-
       tions, for comparing output to manual, it  may  be  helpful  to  switch
       fetchmail  to  English  output  by overriding the locale variables, for
       instance:


              env LC_ALL=C fetchmail # add other options before the hash


              env LANG=en fetchmail # other options before the hash

       or similar. Details vary by operating system.


GENERAL OPERATION
       The behavior of fetchmail is controlled by command-line options  and  a
       run  control file, ~/.fetchmailrc, the syntax of which we describe in a
       later section (this file is  what  the  fetchmailconf  program  edits).
       Command-line options override ~/.fetchmailrc declarations.

       Each  server name that you specify following the options on the command
       line will be queried.  If you do not specify any servers on the command
       line,  each  'poll'  entry in your ~/.fetchmailrc file will be queried,
       unless the idle option is used, which see.

       To facilitate the use of fetchmail in scripts and pipelines, it returns
       an appropriate exit code upon termination -- see EXIT CODES below.

       The  following  options modify the behavior of fetchmail.  It is seldom
       necessary to specify any of these once you have a working  .fetchmailrc
       file set up.

       Almost  all  options  have a corresponding keyword which can be used to
       declare them in a .fetchmailrc file.

       Some special options are not covered here, but are  documented  instead
       in sections on AUTHENTICATION and DAEMON MODE which follow.

   General Options
       -? | --help
              Displays option help.

       -V | --version
              Displays the version information for your copy of fetchmail.  No
              mail fetch is performed.  Instead, for  each  server  specified,
              all  the  option information that would be computed if fetchmail
              were connecting to that server is displayed.  Any non-printables
              in  passwords  or other string names are shown as backslashed C-
              like escape sequences.  This option is useful for verifying that
              your options are set the way you want them.

       -c | --check
              Return  a status code to indicate whether there is mail waiting,
              without actually fetching  or  deleting  mail  (see  EXIT  CODES
              below).  This option turns off daemon mode (in which it would be
              useless).  It doesn't play well with queries to multiple  sites,
              and doesn't work with ETRN or ODMR.  It will return a false pos-
              itive if you leave read but undeleted mail in your server  mail-
              box  and  your  fetch protocol can't tell kept messages from new
              ones.  This means it will work with IMAP, not  work  with  POP2,
              and may occasionally flake out under POP3.

       -s | --silent
              Silent  mode.   Suppresses all progress/status messages that are
              normally echoed to standard output during a fetch (but does  not
              suppress actual error messages).  The --verbose option overrides
              this.

       -v | --verbose
              Verbose mode.  All control messages passed between fetchmail and
              the  mailserver are echoed to stdout.  Overrides --silent.  Dou-
              bling this option (-v -v) causes extra diagnostic information to
              be printed.

       --nosoftbounce
              (since v6.3.10, Keyword: set no softbounce, since v6.3.10)
              Hard  bounce  mode. All permanent delivery errors cause messages
              to be deleted from the  upstream  server,  see  "no  softbounce"
              below.

       --softbounce
              (since v6.3.10, Keyword: set softbounce, since v6.3.10)
              Soft  bounce  mode. All permanent delivery errors cause messages
              to be left on the upstream server if the protocol supports that.
              This  option  is on by default to match historic fetchmail docu-
              mentation, and will be changed to hard bounce mode in  the  next
              fetchmail release.

   Disposal Options
       -a | --all | (since v6.3.3) --fetchall
              (Keyword: fetchall, since v3.0)
              Retrieve  both  old (seen) and new messages from the mailserver.
              The default is to fetch only messages the server has not  marked
              seen.   Under  POP3,  this  option  also  forces the use of RETR
              rather than TOP.  Note that POP2  retrieval  behaves  as  though
              --all  is always on (see RETRIEVAL FAILURE MODES below) and this
              option does not work with ETRN or ODMR.  While the -a and  --all
              command-line and fetchall rcfile options have been supported for
              a long time, the --fetchall command-line  option  was  added  in
              v6.3.3.

       -k | --keep
              (Keyword: keep)
              Keep  retrieved  messages  on  the remote mailserver.  Normally,
              messages are deleted from the folder  on  the  mailserver  after
              they  have  been  retrieved.   Specifying the keep option causes
              retrieved messages to remain in your folder on  the  mailserver.
              This  option does not work with ETRN or ODMR. If used with POP3,
              it is recommended to also specify the --uidl option or uidl key-
              word.

       -K | --nokeep
              (Keyword: nokeep)
              Delete  retrieved  messages  from  the  remote mailserver.  This
              option forces retrieved mail to be deleted.  It may be useful if
              you have specified a default of keep in your .fetchmailrc.  This
              option is forced on with ETRN and ODMR.

       -F | --flush
              (Keyword: flush)
              POP3/IMAP only.  This is a dangerous option and can  cause  mail
              loss  when  used improperly. It deletes old (seen) messages from
              the mailserver before retrieving new  messages.   Warning:  This
              can  cause  mail  loss if you check your mail with other clients
              than fetchmail, and cause fetchmail to delete a message  it  had
              never  fetched  before.  It can also cause mail loss if the mail
              server marks the message seen after retrieval  (IMAP2  servers).
              You  should  probably  not use this option in your configuration
              file. If you use it with POP3, you must use the  'uidl'  option.
              What  you  probably  want  is  the default setting: if you don't
              specify '-k', then fetchmail will automatically delete  messages
              after successful delivery.

       --limitflush
              POP3/IMAP  only, since version 6.3.0.  Delete oversized messages
              from the mailserver before retrieving  new  messages.  The  size
              limit  should  be  separately specified with the --limit option.
              This option does not work with ETRN or ODMR.

   Protocol and Query Options
       -p <proto> | --proto <proto> | --protocol <proto>
              (Keyword: proto[col])
              Specify the protocol to use when communicating with  the  remote
              mailserver.   If  no protocol is specified, the default is AUTO.
              proto may be one of the following:

              AUTO   Tries IMAP, POP3, and POP2 (skipping  any  of  these  for
                     which support has not been compiled in).

              POP2   Post Office Protocol 2 (legacy, to be removed from future
                     release)

              POP3   Post Office Protocol 3

              APOP   Use POP3 with old-fashioned MD5-challenge authentication.
                     Considered not resistant to man-in-the-middle attacks.

              RPOP   Use POP3 with RPOP authentication.

              KPOP   Use POP3 with Kerberos V4 authentication on port 1109.

              SDPS   Use POP3 with Demon Internet's SDPS extensions.

              IMAP   IMAP2bis,  IMAP4,  or  IMAP4rev1 (fetchmail automatically
                     detects their capabilities).

              ETRN   Use the ESMTP ETRN option.

              ODMR   Use the the On-Demand Mail Relay ESMTP profile.

       All these alternatives work in basically the  same  way  (communicating
       with standard server daemons to fetch mail already delivered to a mail-
       box on the server) except ETRN and ODMR.  The ETRN mode allows  you  to
       ask  a compliant ESMTP server (such as BSD sendmail at release 8.8.0 or
       higher) to immediately open a sender-SMTP  connection  to  your  client
       machine and begin forwarding any items addressed to your client machine
       in the server's queue of undelivered mail.   The ODMR mode requires  an
       ODMR-capable  server  and  works similarly to ETRN, except that it does
       not require the client machine to have a static DNS.

       -U | --uidl
              (Keyword: uidl)
              Force UIDL use (effective only with  POP3).   Force  client-side
              tracking  of  'newness'  of messages (UIDL stands for "unique ID
              listing" and is described in RFC1939).  Use with 'keep' to use a
              mailbox  as a baby news drop for a group of users. The fact that
              seen messages are skipped is logged,  unless  error  logging  is
              done  through  syslog  while  running in daemon mode.  Note that
              fetchmail may automatically  enable  this  option  depending  on
              upstream server capabilities.  Note also that this option may be
              removed and forced enabled in a future  fetchmail  version.  See
              also: --idfile.

       --idle (since 6.3.3)
              (Keyword: idle, since before 6.0.0)
              Enable IDLE use (effective only with IMAP). Note that this works
              with only one account and one folder  at  a  given  time,  other
              folders  or  accounts will not be polled when idle is in effect!
              While the idle rcfile keyword had  been  supported  for  a  long
              time, the --idle command-line option was added in version 6.3.3.
              IDLE use means that fetchmail tells  the  IMAP  server  to  send
              notice  of  new  messages,  so they can be retrieved sooner than
              would be possible with regular polls.

       -P <portnumber> | --service <servicename>
              (Keyword: service) Since version 6.3.0.
              The service option permits you to specify a service name to con-
              nect  to.   You  can specify a decimal port number here, if your
              services database lacks the required  service-port  assignments.
              See  the  FAQ  item R12 and the --ssl documentation for details.
              This replaces the older --port option.

       Note that this does not magically switch between TLS-wrapped and start-
       tls  modes,  if  you specify a port number or service name here that is
       TLS-wrapped, meaning it starts to negotiate TLS before sending applica-
       tion  data  in  the clear, you may need to specify --ssl on the command
       line or ssl in your rcfile.

       --port <portnumber>
              (Keyword: port)
              Obsolete version of --service that does not take service  names.
              Note: this option may be removed from a future version.

       --principal <principal>
              (Keyword: principal)
              The  principal option permits you to specify a service principal
              for mutual authentication.  This is applicable to POP3  or  IMAP
              with  Kerberos 4 authentication only.  It does not apply to Ker-
              beros 5 or GSSAPI.  This option  may  be  removed  in  a  future
              fetchmail version.

       -t <seconds> | --timeout <seconds>
              (Keyword: timeout)
              The  timeout option allows you to set a server-nonresponse time-
              out in seconds.  If a mailserver does not send a  greeting  mes-
              sage  or  respond  to  commands for the given number of seconds,
              fetchmail will drop the connection to it.  Without such a  time-
              out  fetchmail  might  hang  until the TCP connection times out,
              trying to fetch mail from a down host, which may be  very  long.
              This  would  be particularly annoying for a fetchmail running in
              the background.  There is a default timeout which  fetchmail  -V
              will  report.   If a given connection receives too many timeouts
              in succession, fetchmail will consider it wedged and stop retry-
              ing.   The  calling  user will be notified by email if this hap-
              pens.

              Beginning with fetchmail 6.3.10, the SMTP client uses the recom-
              mended  minimum  timeouts  from  RFC-5321  while waiting for the
              SMTP/LMTP server it is talking to.  You can raise  the  timeouts
              even  more,  but  you  cannot  shorten  them. This is to avoid a
              painful situation where fetchmail has  been  configured  with  a
              short  timeout  (a  minute  or less), ships a long message (many
              MBytes) to the local MTA, which then takes longer  than  timeout
              to  respond  "OK", which it eventually will; that would mean the
              mail gets delivered properly, but fetchmail cannot notice it and
              will thus refetch this big message over and over again.

       --plugin <command>
              (Keyword: plugin)
              The  plugin  option  allows  you  to  use an external program to
              establish the TCP connection.  This is useful if you want to use
              ssh,  or  need some special firewalling setup.  The program will
              be looked up in $PATH and can optionally be passed the  hostname
              and  port  as  arguments  using "%h" and "%p" respectively (note
              that the interpolation logic  is  rather  primitive,  and  these
              tokens  must  be bounded by whitespace or beginning of string or
              end of string).  Fetchmail will write to the plugin's stdin  and
              read from the plugin's stdout.

       --plugout <command>
              (Keyword: plugout)
              Identical  to  the plugin option above, but this one is used for
              the SMTP connections.

       -r <name> | --folder <name>
              (Keyword: folder[s])
              Causes a specified non-default mail folder on the mailserver (or
              comma-separated list of folders) to be retrieved.  The syntax of
              the folder name is server-dependent.  This option is not  avail-
              able under POP3, ETRN, or ODMR.

       --tracepolls
              (Keyword: tracepolls)
              Tell  fetchmail  to  poll trace information in the form 'polling
              account %s' and 'folder %s' to the Received line  it  generates,
              where  the  %s parts are replaced by the user's remote name, the
              poll label,  and  the  folder  (mailbox)  where  available  (the
              Received  header also normally includes the server's true name).
              This can be used to  facilitate  mail  filtering  based  on  the
              account  it  is  being  received from. The folder information is
              written only since version 6.3.4.

       --ssl  (Keyword: ssl)
              Causes the connection to the mail server  to  be  encrypted  via
              SSL,  by  negotiating SSL directly after connecting (called SSL-
              wrapped mode, or Implicit TLS  by  RFC-8314).   Please  see  the
              description  of --sslproto below!  More information is available
              in the README.SSL file that ships with fetchmail.

              Note that even if this option is omitted,  fetchmail  may  still
              negotiate  SSL  in-band  for  POP3  or IMAP, through the STLS or
              STARTTLS feature.  You can use the --sslproto option  to  modify
              that behavior.

              If no port is specified, the connection is attempted to the well
              known port of the SSL version of the  base  protocol.   This  is
              generally a different port than the port used by the base proto-
              col.  For IMAP, this is port 143 for the clear protocol and port
              993  for  the SSL secured protocol; for POP3, it is port 110 for
              the clear text and port 995 for the encrypted variant.

              If your system lacks the corresponding  entries  from  /etc/ser-
              vices,  see  the  --service  option and specify the numeric port
              number as given in the previous paragraph (unless your  ISP  had
              directed you to different ports, which is uncommon however).

       --sslcert <name>
              (Keyword: sslcert)
              For certificate-based client authentication.  Some SSL encrypted
              servers require client side keys and certificates for  authenti-
              cation.   In  most  cases, this is optional.  This specifies the
              location of the public key certificate to be  presented  to  the
              server  at  the  time the SSL session is established.  It is not
              required (but may be provided) if the server  does  not  require
              it.   It  may  be the same file as the private key (combined key
              and certificate file) but this  is  not  recommended.  Also  see
              --sslkey below.

              NOTE: If you use client authentication, the user name is fetched
              from the certificate's CommonName and  overrides  the  name  set
              with --user.

       --sslkey <name>
              (Keyword: sslkey)
              Specifies  the  file  name  of  the client side private SSL key.
              Some SSL encrypted servers require client side keys and certifi-
              cates  for  authentication.   In  most  cases, this is optional.
              This specifies the location of the  private  key  used  to  sign
              transactions  with  the  server  at  the time the SSL session is
              established.  It is not required (but may be  provided)  if  the
              server  does not require it. It may be the same file as the pub-
              lic key (combined key and certificate file) but this is not rec-
              ommended.

              If a password is required to unlock the key, it will be prompted
              for at the time just prior to establishing the  session  to  the
              server.  This can cause some complications in daemon mode.

              Also see --sslcert above.

       --sslproto <value>
              (Keyword: sslproto, NOTE: semantic changes since v6.4.0)
              This option has a dual use, out of historic fetchmail behaviour.
              It controls both the SSL/TLS protocol version and, if  --ssl  is
              not specified, the STARTTLS behaviour (upgrading the protocol to
              an SSL or TLS connection in-band). Some other options  may  how-
              ever make TLS mandatory.

              Only if this option and --ssl are both missing for a poll, there
              will be opportunistic TLS for POP3  and  IMAP,  where  fetchmail
              will attempt to upgrade to TLSv1 or newer.

              Recognized  values  for  --sslproto  are given below. You should
              normally chose  one  of  the  auto-negotiating  options,  i.  e.
              'tls1.2+'  or Note that depending on OpenSSL library version and
              configuration, some options cause run-time  errors  because  the
              requested  SSL or TLS versions are not supported by the particu-
              lar installed OpenSSL library.

              'TLS1.2+'
                     (default in Oracle Solaris since v6.4.22). Since  v6.4.0.
                     Require TLS. Auto-negotiate TLSv1.2 or newer.

              'auto' SSLv3  downgrade.  (fetchmail 6.3.26 and older have auto-
                     negotiated all protocols that their OpenSSL library  sup-
                     ported, including the broken SSLv3).

              '', the empty string
                     Disable  STARTTLS. If --ssl is given for the same server,
                     log an error  and  pretend  that  'auto'  had  been  used
                     instead.

              'SSL23'
                     see 'auto'.

              'SSL3' Require  SSLv3 exactly. SSLv3 is broken, not supported on
                     all systems, avoid it if possible.  This will make fetch-
                     mail  negotiate  SSLv3  only, and is the only way besides
                     'SSL3+' to have fetchmail 6.4.0 or newer permit SSLv3.

              'SSL3+'
                     same as 'auto', but permit SSLv3 as  well.  This  is  the
                     only  way besides 'SSL3' to have fetchmail 6.4.0 or newer
                     permit SSLv3.

              'TLS1' Require TLSv1. This does not negotiate TLSv1.1 or  newer,
                     and  is  discouraged.  Replace by TLS1+ unless the latter
                     chokes your server.

              'TLS1+'
                     Since v6.4.0. See 'auto'.

              'TLS1.1'
                     Since v6.4.0. Require TLS v1.1 exactly.

              'TLS1.1+'
                     Since v6.4.0.  Require  TLS.  Auto-negotiate  TLSv1.1  or
                     newer.

              'TLS1.2'
                     Since v6.4.0. Require TLS v1.2 exactly.

              'TLS1.3'
                     Since v6.4.0. Require TLS v1.3 exactly.

              'TLS1.3+'
                     Since  v6.4.0.  Require  TLS.  Auto-negotiate  TLSv1.3 or
                     newer.

              Unrecognized parameters
                     are treated the same as 'auto'.

              NOTE: you should hardly ever need to use anything other than  ''
              (to force an unencrypted connection) or 'auto' (to enforce TLS).

       --sslcertck
              (Keyword: sslcertck, default enabled since v6.4.0)
              --sslcertck causes fetchmail to require that SSL/TLS be used and
              disconnect if it can not successfully negotiate SSL or  TLS,  or
              if  it  cannot  successfully verify and validate the certificate
              and follow it to a trust anchor (or trusted  root  certificate).
              The  trust  anchors are given as a set of local trusted certifi-
              cates (see the sslcertfile  and  sslcertpath  options).  If  the
              server certificate cannot be obtained or is not signed by one of
              the trusted ones (directly or indirectly), fetchmail  will  dis-
              connect, regardless of the sslfingerprint option.

              Note  that CRL (certificate revocation lists) are only supported
              in OpenSSL 0.9.7 and newer! Your system  clock  should  also  be
              reasonably accurate when using this option.

       --nosslcertck
              (Keyword: no sslcertck, only in v6.4.X)
              The  opposite  of  --sslcertck, this is a discouraged option. It
              permits fetchmail to continue connecting even if the server cer-
              tificate  failed  the  verification checks.  Should only be used
              together with --sslfingerprint.

       --sslcertfile <file>
              (Keyword: sslcertfile, since v6.3.17)
              Sets the file fetchmail uses to look up local certificates.  The
              default  is  empty.  This can be given in addition to --sslcert-
              path below, and certificates specified in --sslcertfile will  be
              processed before those in --sslcertpath.  The option can be used
              in addition to --sslcertpath.

              The file is a  text  file.  It  contains  the  concatenation  of
              trusted CA certificates in PEM format.

              Note  that  using  this option will suppress loading the default
              SSL trusted CA certificates file unless you set the  environment
              variable  FETCHMAIL_INCLUDE_DEFAULT_X509_CA_CERTS to a non-empty
              value.

       --sslcertpath <directory>
              (Keyword: sslcertpath)
              Sets the directory fetchmail uses to look up local certificates.
              The  default  is  your  OpenSSL default directory. The directory
              must be hashed the way OpenSSL expects it - every time  you  add
              or  modify  a  certificate in the directory, you need to use the
              c_rehash tool (which comes with OpenSSL in the tools/  subdirec-
              tory).  Also,  after  OpenSSL  upgrades,  you  may  need  to run
              c_rehash; particularly when upgrading from 0.9.X to 1.0.0.

              This can be given in addition to --sslcertfile above, which  see
              for precedence rules.

              Note that using this option will suppress adding the default SSL
              trusted CA certificates directory unless you set the environment
              variable  FETCHMAIL_INCLUDE_DEFAULT_X509_CA_CERTS to a non-empty
              value.

       --sslcommonname <common name>
              (Keyword: sslcommonname; since v6.3.9)
              Use of this option is discouraged. Before using it, contact  the
              administrator  of  your upstream server and ask for a proper SSL
              certificate to be used. If that cannot be attained, this  option
              can  be  used  to  specify  the name (CommonName) that fetchmail
              expects on  the  server  certificate.   A  correctly  configured
              server  will  have  this  set  to  the  hostname  by which it is
              reached, and by default fetchmail will expect as much. Use  this
              option  when the CommonName is set to some other value, to avoid
              the "Server  CommonName  mismatch"  warning,  and  only  if  the
              upstream server can't be made to use proper certificates.

       --sslfingerprint <fingerprint>
              (Keyword: sslfingerprint)
              Specify  the  fingerprint  of the server key (an MD5 hash of the
              key) in hexadecimal notation with colons  separating  groups  of
              two digits. The letter hex digits must be in upper case. This is
              the format that fetchmail uses to report the fingerprint when an
              SSL connection is established. When this is specified, fetchmail
              will compare the server key fingerprint with the given one,  and
              the connection will fail if they do not match, regardless of the
              sslcertck setting. The connection will also  fail  if  fetchmail
              cannot  obtain  an SSL certificate from the server.  This can be
              used to prevent man-in-the-middle attacks, but the finger  print
              from the server must be obtained or verified over a secure chan-
              nel, and certainly not over the same  Internet  connection  that
              fetchmail would use.

              Using this option will prevent printing certificate verification
              errors as long as --nosslcertck is in effect.

              To obtain the fingerprint of a certificate stored  in  the  file
              cert.pem, try:

                   openssl x509 -in cert.pem -noout -md5 -fingerprint

              For details, see x509(1ssl).

   Delivery Control Options
       -S <hosts> | --smtphost <hosts>
              (Keyword: smtp[host])
              Specify  a  hunt  list  of hosts to forward mail to (one or more
              hostnames, comma-separated). Hosts are tried in list order;  the
              first  one that is up becomes the forwarding target for the cur-
              rent run.  If this option is not specified, 'localhost' is  used
              as  the default.  Each hostname may have a port number following
              the host name.  The port number is separated from the host  name
              by a slash; the default port is "smtp".  If you specify an abso-
              lute path name (beginning with a /), it will be  interpreted  as
              the name of a UNIX socket accepting LMTP connections (such as is
              supported by the Cyrus IMAP daemon) Example:

                   --smtphost server1,server2/2525,server3,/var/imap/socket/lmtp

              This option can be used with ODMR, and  will  make  fetchmail  a
              relay between the ODMR server and SMTP or LMTP receiver.

              WARNING:  if  you use address numeric IP addresses here, be sure
              to use --smtpaddress or --smtpname (either of which see) with  a
              valid SMTP address literal!

       --fetchdomains <hosts>
              (Keyword: fetchdomains)
              In  ETRN or ODMR mode, this option specifies the list of domains
              the server should ship mail for once the  connection  is  turned
              around.   The  default is the FQDN of the machine running fetch-
              mail.

       -D <domain> | --smtpaddress <domain>
              (Keyword: smtpaddress)
              Specify the domain to be appended to addresses in RCPT TO  lines
              shipped  to  SMTP.  When  this is not specified, the name of the
              SMTP server (as specified by --smtphost) is used  for  SMTP/LMTP
              and 'localhost' is used for UNIX socket/BSMTP.

              NOTE:  if  you  intend  to  use  numeric addresses, or so-called
              address literals per the SMTP standard,  write  them  in  proper
              SMTP  syntax, for instance --smtpaddress "[192.0.2.6]" or --smt-
              paddress "[IPv6:2001:DB8::6]".

       --smtpname <user@domain>
              (Keyword: smtpname)
              Specify the domain and user to be put in RCPT TO  lines  shipped
              to  SMTP.   The  default  user is the current local user. Please
              also see the  NOTE  about  --smtpaddress  and  address  literals
              above.

       -Z <nnn> | --antispam <nnn[, nnn]...>
              (Keyword: antispam)
              Specifies  the list of numeric SMTP errors that are to be inter-
              preted as a spam-block response from the listener.  A  value  of
              -1  disables this option.  For the command-line option, the list
              values should be comma-separated.  Note that the antispam values
              only  apply  to "MAIL FROM" responses in the SMTP/LMTP dialogue,
              but several MTAs (Postfix in its default  configuration,  qmail)
              defer  the  anti-spam  response  code  until  after the RCPT TO.
              --antispam does not  work  in  these  circumstances.   Also  see
              --softbounce (default) and its inverse.

       -m <command> | --mda <command>
              (Keyword: mda)
              This option lets fetchmail use a Message or Local Delivery Agent
              (MDA or LDA) directly, rather than forward via SMTP or LMTP.

              To avoid losing mail, use this option only with MDAs like  mail-
              drop  or  MTAs  like sendmail that exit with a nonzero status on
              disk-full and other delivery errors; the  nonzero  status  tells
              fetchmail  that  delivery  failed  and prevents the message from
              being deleted on the server.

              If fetchmail is running as root,  it  sets  its  user  id  while
              delivering  mail  through  an MDA as follows:  First, the FETCH-
              MAILUSER, LOGNAME, and USER environment variables are checked in
              this  order.  The value of the first variable from his list that
              is defined (even if it is empty!) is looked  up  in  the  system
              user  database.  If  none of the variables is defined, fetchmail
              will use the real user id it was started with.  If  one  of  the
              variables  was  defined,  but the user stated there isn't found,
              fetchmail continues running as root, without checking  remaining
              variables  on the list.  Practically, this means that if you run
              fetchmail as root (not recommended), it is most useful to define
              the  FETCHMAILUSER environment variable to set the user that the
              MDA should run as. Some MDAs (such as maildrop) are designed  to
              be  setuid  root  and  setuid to the recipient's user id, so you
              don't lose functionality this way even when running fetchmail as
              unprivileged user.  Check the MDA's manual for details.

              Some  possible  MDAs  are  "/usr/sbin/sendmail  -i  -f %F -- %T"
              (Note: some several older or vendor sendmail versions mistake --
              for  an address, rather than an indicator to mark the end of the
              option arguments), "/usr/bin/deliver" and "/usr/bin/maildrop  -d
              %T".   Local  delivery  addresses  will be inserted into the MDA
              command wherever you place a %T; the mail message's From address
              will be inserted where you place an %F.

              Do  NOT  enclose the %F or %T string in single quotes!  For both
              %T and %F, fetchmail encloses the  addresses  in  single  quotes
              ('),  after  removing any single quotes they may contain, before
              the MDA command is passed to the shell.

              Do NOT use an MDA invocation that dispatches on the contents  of
              To/Cc/Bcc, like "sendmail -i -t" or "qmail-inject", it will cre-
              ate mail loops and bring the just wrath of many postmasters down
              upon  your head.  This is one of the most frequent configuration
              errors!

              Also, do not try to combine multidrop mode with an MDA  such  as
              maildrop  that can only accept one address, unless your upstream
              stores one copy of the message per recipient and transports  the
              envelope recipient in a header; you will lose mail.

              The  well-known  procmail(1)  package  is very hard to configure
              properly, it has a very nasty "fall through to  the  next  rule"
              behavior on delivery errors (even temporary ones, such as out of
              disk space if another user's  mail  daemon  copies  the  mailbox
              around  to  purge old messages), so your mail will end up in the
              wrong mailbox sooner or later. The proper procmail configuration
              is outside the scope of this document. Using maildrop(1) is usu-
              ally much easier, and many users find the filter syntax used  by
              maildrop easier to understand.

              Finally,  we  strongly  advise that you do not use qmail-inject.
              The command line interface  is  non-standard  without  providing
              benefits  for  typical  use,  and fetchmail makes no attempts to
              accommodate qmail-inject's deviations from the standard. Some of
              qmail-inject's command-line and environment options are actually
              dangerous and can cause broken threads,  non-detected  duplicate
              messages and forwarding loops.


       --lmtp (Keyword: lmtp)
              Cause  delivery via LMTP (Local Mail Transfer Protocol).  A ser-
              vice host and port must be explicitly specified on each host  in
              the  smtphost  hunt list (see above) if this option is selected;
              the default port 25 will (in accordance with RFC  2033)  not  be
              accepted.

       --bsmtp <filename>
              (Keyword: bsmtp)
              Append  fetched  mail to a BSMTP file.  This simply contains the
              SMTP commands that would normally be generated by fetchmail when
              passing mail to an SMTP listener daemon.

              An  argument of '-' causes the SMTP batch to be written to stan-
              dard output, which is of limited use: this only makes sense  for
              debugging, because fetchmail's regular output is interspersed on
              the same channel, so this isn't suitable for mail delivery. This
              special mode may be removed in a later release.

              Note  that  fetchmail's  reconstruction of MAIL FROM and RCPT TO
              lines is not guaranteed correct; the caveats discussed under THE
              USE AND ABUSE OF MULTIDROP MAILBOXES below apply.  This mode has
              precedence before --mda and SMTP/LMTP.

       --bad-header {reject|accept}
              (Keyword: bad-header; since v6.3.15)
              Specify how fetchmail is supposed to  treat  messages  with  bad
              headers, i. e. headers with bad syntax. Traditionally, fetchmail
              has rejected  such  messages,  but  some  distributors  modified
              fetchmail  to accept them. You can now configure fetchmail's be-
              haviour per server.


   Resource Limit Control Options
       -l <maxbytes> | --limit <maxbytes>
              (Keyword: limit)
              Takes a maximum octet size argument, where 0 is the default  and
              also the special value designating "no limit".  If nonzero, mes-
              sages larger than this size will not be fetched and will be left
              on  the  server  (in  foreground sessions, the progress messages
              will note that they are "oversized").   If  the  fetch  protocol
              permits  (in particular, under IMAP or POP3 without the fetchall
              option) the message will not be marked seen.

              An explicit --limit of 0 overrides any limits set  in  your  run
              control  file.  This  option  is  intended  for those needing to
              strictly control fetch time due to expensive and variable  phone
              rates.

              Combined  with  --limitflush, it can be used to delete oversized
              messages waiting on a server.  In daemon mode, oversize  notifi-
              cations  are  mailed  to  the  calling  user (see the --warnings
              option). This option does not work with ETRN or ODMR.

       -w <interval> | --warnings <interval>
              (Keyword: warnings)
              Takes an interval in seconds.  When you call  fetchmail  with  a
              'limit'  option  in  daemon  mode, this controls the interval at
              which warnings about oversized messages are mailed to the  call-
              ing  user  (or  the  user specified by the 'postmaster' option).
              One such notification is always mailed at the  end  of  the  the
              first  poll that the oversized message is detected.  Thereafter,
              re-notification is suppressed until after the  warning  interval
              elapses  (it  will  take place at the end of the first following
              poll).

       -b <count> | --batchlimit <count>
              (Keyword: batchlimit)
              Specify the maximum number of messages that will be  shipped  to
              an SMTP listener before the connection is deliberately torn down
              and rebuilt (defaults to 0,  meaning  no  limit).   An  explicit
              --batchlimit  of  0 overrides any limits set in your run control
              file.  While sendmail(8) normally initiates delivery of  a  mes-
              sage  immediately  after  receiving the message terminator, some
              SMTP listeners are not so prompt.  MTAs like smail(8)  may  wait
              till the delivery socket is shut down to deliver.  This may pro-
              duce annoying delays when fetchmail  is  processing  very  large
              batches.  Setting the batch limit to some nonzero size will pre-
              vent these delays.  This option does not work with ETRN or ODMR.

       -B <number> | --fetchlimit <number>
              (Keyword: fetchlimit)
              Limit the number of messages accepted from a given server  in  a
              single poll.  By default there is no limit. An explicit --fetch-
              limit of 0 overrides any limits set in your  run  control  file.
              This option does not work with ETRN or ODMR.

       --fetchsizelimit <number>
              (Keyword: fetchsizelimit)
              Limit  the  number  of  sizes  of messages accepted from a given
              server in a single transaction.  This option is useful in reduc-
              ing  the  delay in downloading the first mail when there are too
              many mails in the mailbox.  By default, the limit  is  100.   If
              set  to  0,  sizes  of all messages are downloaded at the start.
              This option does not work with ETRN or ODMR.  For POP3, the only
              valid non-zero value is 1.

       --fastuidl <number>
              (Keyword: fastuidl)
              Do  a  binary instead of linear search for the first unseen UID.
              Binary search avoids downloading the UIDs  of  all  mails.  This
              saves  time  (especially  in  daemon mode) where downloading the
              same set of UIDs in each poll is a waste of bandwidth. The  num-
              ber  'n' indicates how rarely a linear search should be done. In
              daemon mode, linear search  is  used  once  followed  by  binary
              searches  in 'n-1' polls if 'n' is greater than 1; binary search
              is always used if 'n' is 1; linear search is always used if  'n'
              is  0.  In  non-daemon  mode, binary search is used if 'n' is 1;
              otherwise linear search is used. The default value of 'n' is  4.
              This option works with POP3 only.

       -e <count> | --expunge <count>
              (Keyword: expunge)
              Arrange  for  deletions to be made final after a given number of
              messages.  Under POP2 or POP3, fetchmail cannot  make  deletions
              final  without  sending QUIT and ending the session -- with this
              option on, fetchmail will break a long  mail  retrieval  session
              into multiple sub-sessions, sending QUIT after each sub-session.
              This is a good defense  against  line  drops  on  POP3  servers.
              Under  IMAP,  fetchmail normally issues an EXPUNGE command after
              each deletion in order to force the deletion to be done  immedi-
              ately.   This  is  safest  when your connection to the server is
              flaky and expensive, as it avoids resending duplicate mail after
              a  line  hit.   However,  on large mailboxes the overhead of re-
              indexing after every message can slam the server pretty hard, so
              if  your  connection  is reliable it is good to do expunges less
              frequently.  Also note that some servers enforce a  delay  of  a
              few seconds after each quit, so fetchmail may not be able to get
              back in immediately after an expunge -- you may see "lock  busy"
              errors if this happens. If you specify this option to an integer
              N, it tells fetchmail  to  only  issue  expunges  on  every  Nth
              delete.  An argument of zero suppresses expunges entirely (so no
              expunges at all will be done until the end of run).  This option
              does not work with ETRN or ODMR.


   Authentication Options
       -u <name> | --user <name> | --username <name>
              (Keyword: user[name])
              Specifies  the user identification to be used when logging in to
              the mailserver.  The appropriate  user  identification  is  both
              server  and  user-dependent.   The default is your login name on
              the client machine that is running fetchmail.  See USER  AUTHEN-
              TICATION below for a complete description.

       -I <specification> | --interface <specification>
              (Keyword: interface)
              Require  that  a specific interface device be up and have a spe-
              cific local or remote IPv4 (IPv6 is not supported by this option
              yet) address (or range) before polling.  Frequently fetchmail is
              used over a transient  point-to-point  TCP/IP  link  established
              directly  to a mailserver via SLIP or PPP.  That is a relatively
              secure channel.  But when other TCP/IP routes to the  mailserver
              exist  (e.g.  when  the  link is connected to an alternate ISP),
              your username and password may be vulnerable to snooping  (espe-
              cially when daemon mode automatically polls for mail, shipping a
              clear password over the  net  at  predictable  intervals).   The
              --interface option may be used to prevent this.  When the speci-
              fied link is not up  or  is  not  connected  to  a  matching  IP
              address, polling will be skipped.  The format is:

                   interface/iii.iii.iii.iii[/mmm.mmm.mmm.mmm]

              The  field  before  the  first slash is the interface name (i.e.
              sl0, ppp0 etc.).  The field  before  the  second  slash  is  the
              acceptable  IP  address.   The field after the second slash is a
              mask which specifies a range of IP addresses to accept.   If  no
              mask  is  present  255.255.255.255  is  assumed  (i.e.  an exact
              match).  This option is currently only supported under Linux and
              FreeBSD.  Please  see  the monitor section for below for FreeBSD
              specific information.

              Note that this option may be removed  from  a  future  fetchmail
              version.

       -M <interface> | --monitor <interface>
              (Keyword: monitor)
              Daemon  mode  can  cause transient links which are automatically
              taken down after a period of  inactivity  (e.g.  PPP  links)  to
              remain  up indefinitely.  This option identifies a system TCP/IP
              interface to be monitored for activity.  After each poll  inter-
              val, if the link is up but no other activity has occurred on the
              link, then the poll will be skipped.  However, when fetchmail is
              woken  up by a signal, the monitor check is skipped and the poll
              goes through unconditionally.  This  option  is  currently  only
              supported  under  Linux and FreeBSD.  For the monitor and inter-
              face options to work for  non  root  users  under  FreeBSD,  the
              fetchmail  binary  must be installed SGID kmem.  This would be a
              security hole, but fetchmail runs with the effective GID set  to
              that  of  the  kmem group only when interface data is being col-
              lected.

              Note that this option may be removed  from  a  future  fetchmail
              version.

       --auth <type>
              (Keyword: auth[enticate])
              This  option  permits you to specify an authentication type (see
              USER AUTHENTICATION below for details).  The possible values are
              any,  password,  kerberos_v5,  kerberos  (or,  for  excruciating
              exactness, kerberos_v4), gssapi, cram-md5, otp, ntlm, msn  (only
              for POP3), external (only IMAP) and ssh.  When any (the default)
              is specified, fetchmail tries first methods that don't require a
              password  (EXTERNAL,  GSSAPI,  KERBEROS IV, KERBEROS 5); then it
              looks for methods that mask your password (CRAM-MD5, NTLM, X-OTP
              - note that MSN is only supported for POP3, but not autoprobed);
              and only if the server doesn't support any of those will it ship
              your password en clair.  Other values may be used to force vari-
              ous authentication methods (ssh suppresses authentication and is
              thus useful for IMAP PREAUTH).  (external suppresses authentica-
              tion and is thus useful for IMAP  EXTERNAL).   Any  value  other
              than password, cram-md5, ntlm, msn or otp suppresses fetchmail's
              normal inquiry for a password.  Specify ssh when you  are  using
              an  end-to-end  secure connection such as an ssh tunnel; specify
              external when you use TLS with client authentication and specify
              gssapi  or  kerberos_v4 if you are using a protocol variant that
              employs GSSAPI or  K4.   Choosing  KPOP  protocol  automatically
              selects Kerberos authentication.  This option does not work with
              ETRN.  GSSAPI service names are in line with RFC-2743  and  IANA
              registrations, see Generic Security Service Application Program
              Interface (GSSAPI)/Kerberos/Simple Authentication and Security
              Layer (SASL) Service Names <https://www.iana.org/assignments/
              gssapi-service-names/>.

   Miscellaneous Options
       -f <pathname> | --fetchmailrc <pathname>
              Specify a non-default name for the  ~/.fetchmailrc  run  control
              file.   The pathname argument must be either "-" (a single dash,
              meaning to read the configuration  from  standard  input)  or  a
              filename.   Unless the --version option is also on, a named file
              argument  must  have  permissions  no  more   open   than   0700
              (u=rwx,g=,o=) or else be /dev/null.

       -i <pathname> | --idfile <pathname>
              (Keyword: idfile)
              Specify  an  alternate  name for the .fetchids file used to save
              message UIDs. NOTE: since fetchmail 6.3.0, write access  to  the
              directory containing the idfile is required, as fetchmail writes
              a temporary file and renames it  into  the  place  of  the  real
              idfile only if the temporary file has been written successfully.
              This avoids the truncation of idfiles when running out  of  disk
              space.

       --pidfile <pathname>
              (Keyword: pidfile; since fetchmail v6.3.4)
              Override  the default location of the PID file that is used as a
              lock file.  Default: see "ENVIRONMENT"  below.  Note  that  many
              places  in  the  code and documentation, the term "lock file" is
              used.  This file contains the process ID of the  running  fetch-
              mail  on the first line and potentially the daemon interval on a
              second line.

       -n | --norewrite
              (Keyword: no rewrite)
              Normally, fetchmail edits RFC-822 address headers (To, From, Cc,
              Bcc, and Reply-To) in fetched mail so that any mail IDs local to
              the server are expanded to full addresses (@ and the  mailserver
              hostname  are  appended).  This enables replies on the client to
              get addressed correctly (otherwise your mailer might think  they
              should  be  addressed  to  local  users on the client machine!).
              This option disables the rewrite.  (This option is  provided  to
              pacify  people  who  are  paranoid about having an MTA edit mail
              headers and want to know they can prevent it, but it  is  gener-
              ally  not a good idea to actually turn off rewrite.)  When using
              ETRN or ODMR, the rewrite option is ineffective.

       -E <line> | --envelope <line>
              (Keyword: envelope; Multidrop only)
              In the configuration file, an enhanced syntax is used:
              envelope [<count>] <line>

              This option changes the header fetchmail assumes  will  carry  a
              copy  of the mail's envelope address.  Normally this is 'X-Enve-
              lope-To'.  Other  typically  found  headers  to  carry  envelope
              information  are 'X-Original-To' and 'Delivered-To'.  Now, since
              these headers are not standardized,  practice  varies.  See  the
              discussion  of  multidrop  address handling below.  As a special
              case, 'envelope "Received"' enables  parsing  of  sendmail-style
              Received lines.  This is the default, but discouraged because it
              is not fully reliable.

              Note that fetchmail expects the Received-line to be  in  a  spe-
              cific  format: It must contain "by host for address", where host
              must match one of the mailserver names that fetchmail recognizes
              for the account in question.

              The optional count argument (only available in the configuration
              file) determines how many header lines of this kind are skipped.
              A  count of 1 means: skip the first, take the second. A count of
              2 means: skip the first and second, take the third, and so on.

       -Q <prefix> | --qvirtual <prefix>
              (Keyword: qvirtual; Multidrop only)
              The string prefix assigned to this option will be  removed  from
              the  user  name  found in the header specified with the envelope
              option (before  doing  multidrop  name  mapping  or  localdomain
              checking, if either is applicable). This option is useful if you
              are using fetchmail to collect the mail for an entire domain and
              your  ISP  (or  your  mail redirection provider) is using qmail.
              One of the basic features of qmail is the Delivered-To:  message
              header.  Whenever qmail delivers a message to a local mailbox it
              puts the username and hostname of the envelope recipient on this
              line.   The  major reason for this is to prevent mail loops.  To
              set up qmail to batch mail for a disconnected site the ISP-mail-
              host will have normally put that site in its 'Virtualhosts' con-
              trol file so it will add a prefix to all mail addresses for this
              site.  This  results  in  mail  sent to 'username@userhost.user-
              dom.dom.com' having a Delivered-To: line of the form:

              Delivered-To: mbox-userstr-username@userhost.example.com

              The ISP can make the 'mbox-userstr-' prefix anything they choose
              but  a  string  matching the user host name is likely.  By using
              the option 'envelope Delivered-To:' you can make fetchmail reli-
              ably  identify  the original envelope recipient, but you have to
              strip the 'mbox-userstr-' prefix to deliver to the correct user.
              This is what this option is for.

       --configdump
              Parse   the  ~/.fetchmailrc  file,  interpret  any  command-line
              options specified, and dump a configuration report  to  standard
              output.  The configuration report is a data structure assignment
              in the language Python.  This option is meant to be used with an
              interactive ~/.fetchmailrc editor like fetchmailconf, written in
              Python.

       -y | --yydebug
              Enables parser debugging, this option is meant  to  be  used  by
              developers only.


   Removed Options
       -T | --netsec
              Removed before version 6.3.0, the required underlying inet6_apps
              library had been discontinued and is no longer available.


USER AUTHENTICATION AND ENCRYPTION
       All modes except ETRN require  authentication  of  the  client  to  the
       server.   Normal user authentication in fetchmail is very much like the
       authentication mechanism of ftp(1).  The correct user-id  and  password
       depend upon the underlying security system at the mailserver.

       If  the mailserver is a Unix machine on which you have an ordinary user
       account, your regular login name and password are used with  fetchmail.
       If  you  use  the  same  login  name  on both the server and the client
       machines, you needn't worry about specifying  a  user-id  with  the  -u
       option  -- the default behavior is to use your login name on the client
       machine as the user-id on the server machine.  If you use  a  different
       login  name  on the server machine, specify that login name with the -u
       option.  e.g. if your login name is 'jsmith' on a machine named  'mail-
       grunt', you would start fetchmail as follows:

              fetchmail -u jsmith mailgrunt

       The  default behavior of fetchmail is to prompt you for your mailserver
       password before the connection is established.  This is the safest  way
       to  use  fetchmail  and  ensures that your password will not be compro-
       mised.  You may also specify your password in your ~/.fetchmailrc file.
       This is convenient when using fetchmail in daemon mode or with scripts.


   Using netrc files
       If you do not specify a password, and fetchmail cannot extract one from
       your ~/.fetchmailrc file, it will look for a ~/.netrc file in your home
       directory before requesting one interactively; if an entry matching the
       mailserver is found in that file, the password will be used.  Fetchmail
       first looks for a match on poll name; if it finds none, it checks for a
       match on via name.  See the ftp(1) man page for details of  the  syntax
       of the ~/.netrc file.  To show a practical example, a .netrc might look
       like this:

              machine hermes.example.org
              login joe
              password topsecret

       You can repeat this block with different user information if  you  need
       to provide more than one password.

       This feature may allow you to avoid duplicating password information in
       more than one file.

       On mailservers that do not provide ordinary user accounts, your user-id
       and  password are usually assigned by the server administrator when you
       apply for a mailbox on the server.  Contact your  server  administrator
       if  you  don't  know  the correct user-id and password for your mailbox
       account.


   Secure Socket Layers (SSL) and Transport Layer Security (TLS)
       All retrieval protocols can use SSL or TLS wrapping for the  transport.
       Additionally,  POP3  and  IMAP  retrival  can also negotiate SSL/TLS by
       means of STARTTLS (or STLS).

       Note that fetchmail currently uses the OpenSSL library,  which  is  se-
       verely underdocumented, so failures may occur just because the program-
       mers are not aware of OpenSSL's requirement of the day.  For  instance,
       since  v6.3.16,  fetchmail calls OpenSSL_add_all_algorithms(), which is
       necessary to support certificates using SHA256 on OpenSSL 0.9.8 -- this
       information  is deeply hidden in the documentation and not at all obvi-
       ous.  Please do not hesitate to report subtle SSL failures.

       You can access SSL encrypted services by specifying the options  start-
       ing  with  --ssl,  such  as --ssl, --sslproto, --sslcertck, and others.
       You can also do this  using  the  corresponding  user  options  in  the
       .fetchmailrc  file.  Some services, such as POP3 and IMAP, have differ-
       ent well known ports defined  for  the  SSL  encrypted  services.   The
       encrypted  ports will be selected automatically when SSL is enabled and
       no explicit port is specified.   Also, the --sslcertck command line  or
       sslcertck  run  control file option should be used to force strict cer-
       tificate checking with older fetchmail versions - see below.

       If SSL is not configured, fetchmail will usually opportunistically  try
       to  use STARTTLS. STARTTLS can be enforced by using --sslproto auto and
       defeated by using --sslproto ''.  TLS connections use the same port  as
       the  unencrypted  version of the protocol and negotiate TLS via special
       command. The --sslcertck command line or  sslcertck  run  control  file
       option should be used to force strict certificate checking - see below.

       --sslcertck  is recommended: When connecting to an SSL or TLS encrypted
       server, the server presents a certificate to the client for validation.
       The  certificate  is checked to verify that the common name in the cer-
       tificate matches the name of the server being contacted  and  that  the
       effective  and  expiration dates in the certificate indicate that it is
       currently valid.  If any of these checks fail,  a  warning  message  is
       printed, but the connection continues.  The server certificate does not
       need to be signed by any specific Certifying Authority  and  may  be  a
       "self-signed"  certificate.  If  the --sslcertck command line option or
       sslcertck run control file option is used, fetchmail will instead abort
       if  any  of  these  checks fail, because it must assume that there is a
       man-in-the-middle attack in this scenario,  hence  fetchmail  must  not
       expose  cleartext passwords. Use of the sslcertck or --sslcertck option
       is therefore advised; it has become the default in fetchmail 6.4.0.

       Some SSL encrypted servers may request a client  side  certificate.   A
       client  side  public  SSL certificate and private SSL key may be speci-
       fied.  If requested by the server, the client certificate  is  sent  to
       the  server  for  validation.   Some servers may require a valid client
       certificate and may refuse connections if a certificate is not provided
       or  if  the  certificate is not valid.  Some servers may require client
       side certificates be signed by a recognized Certifying Authority.   The
       format  for the key files and the certificate files is that required by
       the underlying SSL libraries (OpenSSL in the general case).

       A word of care about the use of SSL: While above mentioned  setup  with
       self-signed  server  certificates  retrieved over the wires can protect
       you from a passive eavesdropper, it  doesn't  help  against  an  active
       attacker.  It's  clearly  an  improvement over sending the passwords in
       clear, but you should be aware that a man-in-the-middle attack is triv-
       ially possible (in particular with tools such as dsniff <https://
       monkey.org/~dugsong/dsniff/>, ).  Use of  strict  certificate  checking
       with a certification authority recognized by server and client, or per-
       haps of an SSH tunnel (see below for some examples)  is  preferable  if
       you care seriously about the security of your mailbox and passwords.


POP3 VARIANTS
       Early  versions  of  POP3  (RFC1081, RFC1225) supported a crude form of
       independent authentication using the .rhosts  file  on  the  mailserver
       side.   Under  this  RPOP  variant, a fixed per-user ID equivalent to a
       password was sent in clear over a link to a  reserved  port,  with  the
       command  RPOP  rather  than  PASS to alert the server that it should do
       special checking.  RPOP is supported  by  fetchmail  (you  can  specify
       'protocol RPOP' to have the program send 'RPOP' rather than 'PASS') but
       its use is strongly discouraged, and support will  be  removed  from  a
       future fetchmail version.  This facility was vulnerable to spoofing and
       was withdrawn in RFC1460.

       RFC1460 introduced APOP authentication.  In this variant of  POP3,  you
       register  an  APOP  password  on your server host (on some servers, the
       program to do this is called popauth(8)).  You put the same password in
       your ~/.fetchmailrc file.  Each time fetchmail logs in, it sends an MD5
       hash of your password and the server greeting time to the server, which
       can verify it by checking its authorization database.

       Note  that  APOP  is no longer considered resistant against man-in-the-
       middle attacks.


   RETR or TOP
       fetchmail makes some efforts to make the server  believe  messages  had
       not  been  retrieved,  by  using the TOP command with a large number of
       lines when possible.  TOP is a command that retrieves the  full  header
       and  a  fetchmail-specified  amount  of  body lines. It is optional and
       therefore not implemented by all servers, and some are known to  imple-
       ment  it  improperly.  On  many servers however, the RETR command which
       retrieves the full message with header and body, sets the  "seen"  flag
       (for instance, in a web interface), whereas the TOP command does not do
       that.

       fetchmail will always use  the  RETR  command  if  "fetchall"  is  set.
       fetchmail will also use the RETR command if "keep" is set and "uidl" is
       unset.  Finally, fetchmail will use the  RETR  command  on  Maillennium
       POP3/PROXY  servers  (used by Comcast) to avoid a deliberate TOP misin-
       terpretation in this server that causes message corruption.

       In all other cases, fetchmail will use the TOP  command.  This  implies
       that in "keep" setups, "uidl" must be set if "TOP" is desired.

       Note  that  this  description is true for the current version of fetch-
       mail, but the behavior may change in future  versions.  In  particular,
       fetchmail  may  prefer  the RETR command because the TOP command causes
       much grief on some servers and is only optional.

ALTERNATE AUTHENTICATION FORMS/METHODS
       If your fetchmail was built with Kerberos support and you specify  Ker-
       beros  authentication  (either  with  --auth or the .fetchmailrc option
       authenticate kerberos_v4) it will try to get a Kerberos ticket from the
       mailserver at the start of each query.  Note: if either the pollname or
       via name is 'hesiod', fetchmail will try to use Hesiod to look  up  the
       mailserver.

       If  you  use  POP3  or  IMAP with GSSAPI authentication, fetchmail will
       expect the server to have RFC1731- or RFC1734-conforming  GSSAPI  capa-
       bility, and will use it.  Currently this has only been tested over Ker-
       beros V, so you're expected to already have a  ticket-granting  ticket.
       You  may  pass  a username different from your principal name using the
       standard --user command or by the .fetchmailrc option user.

       If your IMAP daemon returns the PREAUTH response in its greeting  line,
       fetchmail  will  notice  this  and skip the normal authentication step.
       This can be useful, e.g. if you start imapd explicitly using  ssh.   In
       this  case  you can declare the authentication value 'ssh' on that site
       entry to stop .fetchmail from asking you for a password when it  starts
       up.

       If you use client authentication with TLS1 and your IMAP daemon returns
       the AUTH=EXTERNAL response, fetchmail will notice this and will use the
       authentication  shortcut and will not send the passphrase. In this case
       you can declare the authentication value 'external'
        on that site to stop fetchmail from asking you for a password when  it
       starts up.

       If  you are using POP3, and the server issues a one-time-password chal-
       lenge conforming to RFC1938, fetchmail will use your password as a pass
       phrase  to  generate the required response. This avoids sending secrets
       over the net unencrypted.

       Compuserve's RPA authentication is supported. If  you  compile  in  the
       support,  fetchmail  will try to perform an RPA pass-phrase authentica-
       tion instead of sending over the password en clair if it detects "@com-
       puserve.com" in the hostname.

       If  you are using IMAP, Microsoft's NTLM authentication (used by Micro-
       soft Exchange) is supported. If you compile in the  support,  fetchmail
       will try to perform an NTLM authentication (instead of sending over the
       password en clair) whenever the server returns AUTH=NTLM in  its  capa-
       bility   response.   Specify  a  user  option  value  that  looks  like
       'user@domain': the part to the left of the @  will  be  passed  as  the
       username and the part to the right as the NTLM domain.


   ESMTP AUTH
       fetchmail  also  supports  authentication  to  the  ESMTP server on the
       client side according to RFC 2554.  You  can  specify  a  name/password
       pair  to be used with the keywords 'esmtpname' and 'esmtppassword'; the
       former defaults to the username of the calling user.


DAEMON MODE
   Introducing the daemon mode
       In daemon mode, fetchmail puts itself into the background and runs for-
       ever,  querying  each  specified  host  and  then  sleeping for a given
       polling interval.

   Starting the daemon mode
       There are several ways to make fetchmail work in daemon  mode.  On  the
       command  line,  --daemon <interval> or -d <interval> option runs fetch-
       mail in daemon mode.  You must specify a numeric argument  which  is  a
       polling interval (time to wait after completing a whole poll cycle with
       the last server and before starting the next poll cycle with the  first
       server) in seconds.

       Example: simply invoking

              fetchmail -d 900

       will,  therefore,  poll  all the hosts described in your ~/.fetchmailrc
       file (except those explicitly excluded with the 'skip' verb) a bit less
       often  than  once every 15 minutes (exactly: 15 minutes + time that the
       poll takes).

       It is also possible to set a polling interval  in  your  ~/.fetchmailrc
       file  by saying 'set daemon <interval>', where <interval> is an integer
       number of seconds.  If you do this, fetchmail will always start in dae-
       mon mode unless you override it with the command-line option --daemon 0
       or -d0.

       Only one daemon process is permitted per user; in daemon  mode,  fetch-
       mail  sets  up a per-user lockfile to guarantee this.  (You can however
       cheat and set the FETCHMAILHOME environment variable to  overcome  this
       setting,  but  in that case, it is your responsibility to make sure you
       aren't polling the same server with two processes at the same time.)

   Awakening the background daemon
       Normally, calling fetchmail with a daemon in  the  background  sends  a
       wake-up  signal  to the daemon and quits without output. The background
       daemon then starts its next poll cycle immediately.  The  wake-up  sig-
       nal, SIGUSR1, can also be sent manually. The wake-up action also clears
       any 'wedged' flags indicating  that  connections  have  wedged  due  to
       failed authentication or multiple timeouts.

   Terminating the background daemon
       The  option  -q or --quit will kill a running daemon process instead of
       waking it up (if there is no such process, fetchmail will notify  you).
       If  the  --quit option appears last on the command line, fetchmail will
       kill the running daemon process and  then  quit.  Otherwise,  fetchmail
       will first kill a running daemon process and then continue running with
       the other options.

   Useful options for daemon mode
       The -L <filename> or --logfile <filename> option (keyword: set logfile)
       is  only  effective when fetchmail is detached and in daemon mode. Note
       that the logfile must exist before fetchmail is run, you  can  use  the
       touch(1) command with the filename as its sole argument to create it.
       This  option  allows  you  to redirect status messages into a specified
       logfile (follow the option with the  logfile  name).   The  logfile  is
       opened  for  append, so previous messages aren't deleted.  This is pri-
       marily useful for debugging configurations. Note  that  fetchmail  does
       not  detect  if the logfile is rotated, the logfile is only opened once
       when fetchmail starts. You need to restart fetchmail after rotating the
       logfile and before compressing it (if applicable).

       The --syslog option (keyword: set syslog) allows you to redirect status
       and error messages emitted to the syslog(3) system daemon if available.
       Messages are logged with an id of fetchmail, the facility LOG_MAIL, and
       priorities LOG_ERR, LOG_ALERT or LOG_INFO.  This option is intended for
       logging status and error messages which indicate the status of the dae-
       mon and the results while fetching mail from the server(s).  Error mes-
       sages  for  command  line options and parsing the .fetchmailrc file are
       still written to stderr, or to the specified log file.  The  --nosyslog
       option  turns  off  use  of  syslog(3),  assuming it's turned on in the
       ~/.fetchmailrc file.  This option is overridden, in certain situations,
       by --logfile (which see).

       The  -N or --nodetach option suppresses backgrounding and detachment of
       the daemon process from its  control  terminal.   This  is  useful  for
       debugging  or  when fetchmail runs as the child of a supervisor process
       such as init(8) or Gerrit Pape's runit(8).  Note that this also  causes
       the logfile option to be ignored.

       Note  that  while  running  in  daemon  mode polling a POP2 or IMAP2bis
       server, transient errors (such as DNS  failures  or  sendmail  delivery
       refusals) may force the fetchall option on for the duration of the next
       polling cycle.  This is a robustness feature.  It means that if a  mes-
       sage is fetched (and thus marked seen by the mailserver) but not deliv-
       ered locally due to some transient error, it will be re-fetched  during
       the  next  poll  cycle.   (The IMAP logic doesn't delete messages until
       they're delivered, so this problem does not arise.)

       If you touch or change the ~/.fetchmailrc file while fetchmail is  run-
       ning in daemon mode, this will be detected at the beginning of the next
       poll cycle.  When  a  changed  ~/.fetchmailrc  is  detected,  fetchmail
       rereads  it and restarts from scratch (using exec(2); no state informa-
       tion is retained in the new instance).  Note that if fetchmail needs to
       query  for  passwords,  of  that if you break the ~/.fetchmailrc file's
       syntax, the new instance  will  softly  and  silently  vanish  away  on
       startup.


ADMINISTRATIVE OPTIONS
       The  --postmaster <name> option (keyword: set postmaster) specifies the
       last-resort username to which multidrop mail is to be forwarded  if  no
       matching  local  recipient can be found. It is also used as destination
       of undeliverable mail if the 'bouncemail'  global  option  is  off  and
       additionally for spam-blocked mail if the 'bouncemail' global option is
       off and the 'spambounce' global option is on. This option  defaults  to
       the user who invoked fetchmail.  If the invoking user is root, then the
       default of this option is the user 'postmaster'.  Setting postmaster to
       the  empty string causes such mail as described above to be discarded -
       this however is usually a bad idea.  See also the  description  of  the
       'FETCHMAILUSER' environment variable in the ENVIRONMENT section below.

       The  --nobounce  behaves  like  the  "set no bouncemail" global option,
       which see.

       The --invisible option (keyword: set invisible) tries to make fetchmail
       invisible.   Normally, fetchmail behaves like any other MTA would -- it
       generates a Received header into each message describing its  place  in
       the  chain  of  transmission, and tells the MTA it forwards to that the
       mail came from the machine fetchmail itself  is  running  on.   If  the
       invisible option is on, the Received header is suppressed and fetchmail
       tries to spoof the MTA it forwards to into thinking  it  came  directly
       from the mailserver host.

       The  --showdots option (keyword: set showdots) forces fetchmail to show
       progress dots even if the output goes to a file or fetchmail is not  in
       verbose  mode.   Fetchmail shows the dots by default when run in --ver-
       bose mode and output  goes  to  console.  This  option  is  ignored  in
       --silent mode.

       By  specifying  the  --tracepolls  option, you can ask fetchmail to add
       information to the Received header on the form "polling {label} account
       {user}", where {label} is the account label (from the specified rcfile,
       normally ~/.fetchmailrc) and {user} is the username which  is  used  to
       log  on  to  the mail server. This header can be used to make filtering
       email where no useful header information is available and you want mail
       from  different  accounts  sorted into different mailboxes (this could,
       for example, occur if you have an account on the same server running  a
       mailing  list,  and are subscribed to the list using that account). The
       default is not adding any such header.  In .fetchmailrc, this is called
       'tracepolls'.


RETRIEVAL FAILURE MODES
       The protocols fetchmail uses to talk to mailservers are next to bullet-
       proof.  In normal operation forwarding to port 25, no message  is  ever
       deleted  (or  even marked for deletion) on the host until the SMTP lis-
       tener on the client side has acknowledged to fetchmail that the message
       has been either accepted for delivery or rejected due to a spam block.

       When forwarding to an MDA, however, there is more possibility of error.
       Some MDAs are 'safe' and reliably return a nonzero status on any deliv-
       ery  error, even one due to temporary resource limits.  The maildrop(1)
       program is like this; so are most programs designed as  mail  transport
       agents,  such as sendmail(1), including the sendmail wrapper of Postfix
       and exim(1).  These programs give back a reliable positive acknowledge-
       ment  and  can  be  used with the mda option with no risk of mail loss.
       Unsafe MDAs, though, may return 0 even on delivery  failure.   If  this
       happens, you will lose mail.

       The normal mode of fetchmail is to try to download only 'new' messages,
       leaving untouched  (and  undeleted)  messages  you  have  already  read
       directly  on  the server (or fetched with a previous fetchmail --keep).
       But you may find that messages you've already read on  the  server  are
       being  fetched  (and deleted) even when you don't specify --all.  There
       are several reasons this can happen.

       One could be that you're using POP2.  The  POP2  protocol  includes  no
       representation  of  'new' or 'old' state in messages, so fetchmail must
       treat all messages as new all the time.  But POP2 is obsolete, so  this
       is unlikely.

       A  potential  POP3 problem might be servers that insert messages in the
       middle of mailboxes (some VMS implementations of mail are rumored to do
       this).   The  fetchmail  code assumes that new messages are appended to
       the end of the mailbox; when this is not true it  may  treat  some  old
       messages  as  new and vice versa.  Using UIDL whilst setting fastuidl 0
       might fix this, otherwise, consider switching to IMAP.

       Yet another POP3 problem is that if they can't make  tempfiles  in  the
       user's home directory, some POP3 servers will hand back an undocumented
       response that causes fetchmail to spuriously report "No mail".

       The IMAP code uses the presence or absence of the server flag \Seen  to
       decide  whether or not a message is new.  This isn't the right thing to
       do, fetchmail should check the UIDVALIDITY and use UID, but it  doesn't
       do  that  yet.  Under Unix, it counts on your IMAP server to notice the
       BSD-style Status flags set by mail user agents and set the  \Seen  flag
       from  them when appropriate.  All Unix IMAP servers we know of do this,
       though it's not specified by the IMAP RFCs.  If you ever  trip  over  a
       server that doesn't, the symptom will be that messages you have already
       read on your host will look new to  the  server.   In  this  (unlikely)
       case,  only  messages  you  fetched  with fetchmail --keep will be both
       undeleted and marked old.

       In ETRN and ODMR modes, fetchmail does not actually retrieve  messages;
       instead,  it  asks the server's SMTP listener to start a queue flush to
       the client via SMTP.  Therefore it sends only undelivered messages.


SPAM FILTERING
       Many SMTP listeners allow administrators to set up 'spam filters'  that
       block  unsolicited  email  from specified domains.  A MAIL FROM or DATA
       line that triggers this feature will  elicit  an  SMTP  response  which
       (unfortunately) varies according to the listener.

       Newer versions of sendmail return an error code of 571.

       According  to RFC2821, the correct thing to return in this situation is
       550 "Requested action not taken: mailbox unavailable" (the  draft  adds
       "[E.g.,  mailbox  not  found, no access, or command rejected for policy
       reasons].").

       Older versions of the exim MTA return 501 "Syntax error  in  parameters
       or arguments".

       The postfix MTA runs 554 as an antispam response.

       Zmailer  may  reject  code with a 500 response (followed by an enhanced
       status code that contains more information).

       Return codes which fetchmail treats as antispam responses and  discards
       the  message can be set with the 'antispam' option.  This is one of the
       only three circumstance under which fetchmail ever discards  mail  (the
       others  are the 552 and 553 errors described below, and the suppression
       of multidropped messages with a message-ID already seen).

       If fetchmail is fetching from an IMAP  server,  the  antispam  response
       will be detected and the message rejected immediately after the headers
       have been fetched, without reading the message body.  Thus,  you  won't
       pay for downloading spam message bodies.

       By default, the list of antispam responses is empty.

       If  the spambounce global option is on, mail that is spam-blocked trig-
       gers an RFC1892/RFC1894 bounce message informing the originator that we
       do not accept mail from it. See also BUGS.


SMTP/ESMTP ERROR HANDLING
       Besides  the  spam-blocking  described  above,  fetchmail takes special
       actions -- that may be modified by the --softbounce option  --  on  the
       following SMTP/ESMTP error response codes

       452 (insufficient system storage)
            Leave the message in the server mailbox for later retrieval.

       552 (message exceeds fixed maximum message size)
            Delete the message from the server.  Send bounce-mail to the orig-
            inator.

       553 (invalid sending domain)
            Delete the message from  the  server.   Don't  even  try  to  send
            bounce-mail to the originator.

       Other  errors  greater  or equal to 500 trigger bounce mail back to the
       originator, unless suppressed by --softbounce. See also BUGS.


THE RUN CONTROL FILE
       The preferred way to set up fetchmail is to write a  .fetchmailrc  file
       in  your  home directory (you may do this directly, with a text editor,
       or indirectly via fetchmailconf).  When there is a conflict between the
       command-line arguments and the arguments in this file, the command-line
       arguments take precedence.

       To protect the security of your passwords, your ~/.fetchmailrc may  not
       normally  have more than 0700 (u=rwx,g=,o=) permissions; fetchmail will
       complain and exit otherwise (this check is suppressed when --version is
       on).

       You may read the .fetchmailrc file as a list of commands to be executed
       when fetchmail is called with no arguments.

   Run Control Syntax
       Comments begin with a '#' and extend through the end of the line.  Oth-
       erwise the file consists of a series of server entries or global option
       statements in a free-format, token-oriented syntax.

       There are four kinds of tokens: grammar keywords, numbers (i.e. decimal
       digit  sequences),  unquoted  strings,  and  quoted  strings.  A quoted
       string is bounded by double quotes  and  may  contain  whitespace  (and
       quoted  digits are treated as a string).  Note that quoted strings will
       also contain line feed characters if they run across two or more lines,
       unless  you  use  a  backslash  to join lines (see below).  An unquoted
       string is any  whitespace-delimited  token  that  is  neither  numeric,
       string  quoted  nor  contains  the special characters ',', ';', ':', or
       '='.

       Any amount of whitespace separates tokens in  server  entries,  but  is
       otherwise  ignored.  You may use backslash escape sequences (\n for LF,
       \t for HT, \b for BS, \r for CR, \nnn for  decimal  (where  nnn  cannot
       start with a 0), \0ooo for octal, and \xhh for hex) to embed non-print-
       able characters or string delimiters in strings.  In quoted strings,  a
       backslash at the very end of a line will cause the backslash itself and
       the line feed (LF or NL, new line) character to be ignored, so that you
       can  wrap long strings. Without the backslash at the line end, the line
       feed character would become part of the string.

       Warning: while these resemble C-style escape sequences,  they  are  not
       the  same.  fetchmail only supports these eight styles. C supports more
       escape sequences that consist of backslash (\) and a single  character,
       but  does  not support decimal codes and does not require the leading 0
       in octal notation.  Example: fetchmail interprets \233 the same as \xE9
       (Latin  small  letter  e  with  acute), where C would interpret \233 as
       octal 0233 = \x9B (CSI, control sequence introducer).

       Each server entry consists of one of the  keywords  'poll'  or  'skip',
       followed  by a server name, followed by server options, followed by any
       number of user (or username) descriptions, followed  by  user  options.
       Note:  the  most  common  cause  of syntax errors is mixing up user and
       server options or putting user options before the user descriptions.

       For backward compatibility, the word 'server' is a synonym for 'poll'.

       You can use the noise  keywords  'and',  'with',  'has',  'wants',  and
       'options'  anywhere  in  an entry to make it resemble English.  They're
       ignored, but but can make entries much easier to read at a glance.  The
       punctuation characters ':', ';' and ',' are also ignored.

   Poll vs. Skip
       The  'poll' verb tells fetchmail to query this host when it is run with
       no arguments.  The 'skip' verb tells fetchmail not to  poll  this  host
       unless  it  is  explicitly named on the command line.  (The 'skip' verb
       allows you to experiment with test entries safely,  or  easily  disable
       entries for hosts that are temporarily down.)

   Keyword/Option Summary
       Here are the legal options.  Keyword suffixes enclosed in square brack-
       ets are optional.  Those corresponding to  short  command-line  options
       are  followed  by  '-' and the appropriate option letter.  If option is
       only relevant to a single mode of operation, it is noted as 's' or  'm'
       for singledrop- or multidrop-mode, respectively.

       Here are the legal global options:


       Keyword             Opt   Mode   Function
       --------------------------------------------------------------------
       set daemon          -d           Set  a background poll interval in
                                        seconds.
       set postmaster                   Give the name of  the  last-resort
                                        mail recipient (default: user run-
                                        ning  fetchmail,  "postmaster"  if
                                        run by the root user)
       set    bouncemail                Direct  error  mail  to the sender
                                        (default)
       set no bouncemail                Direct error  mail  to  the  local
                                        postmaster  (as  per the 'postmas-
                                        ter' global option above).
       set no spambounce                Do not  bounce  spam-blocked  mail
                                        (default).
       set    spambounce                Bounce  blocked  spam-blocked mail
                                        (as  per   the   'antispam'   user
                                        option) back to the destination as
                                        indicated  by   the   'bouncemail'
                                        global  option.   Warning:  Do not
                                        use this to bounce  spam  back  to
                                        the  sender  -  most  spam is sent
                                        with false sender address and thus
                                        this    option    hurts   innocent
                                        bystanders.

       set no softbounce                Delete  permanently  undeliverable
                                        mail.  It  is  recommended  to use
                                        this option if  the  configuration
                                        has been thoroughly tested.
       set    softbounce                Keep   permanently   undeliverable
                                        mail as though a  temporary  error
                                        had occurred (default).
       set logfile         -L           Name of a file to append error and
                                        status messages to.   Only  effec-
                                        tive  in daemon mode and if fetch-
                                        mail  detaches.    If   effective,
                                        overrides set syslog.
       set pidfile         -p           Name of the PID file.
       set idfile          -i           Name  of  the  file  to  store UID
                                        lists in.
       set    syslog                    Do  error  logging  through   sys-
                                        log(3).  May  be overridden by set
                                        logfile.
       set no syslog                    Turn  off  error  logging  through
                                        syslog(3). (default)
       set properties                   String  value  that  is ignored by
                                        fetchmail (may be used  by  exten-
                                        sion scripts).

       Here are the legal server options:


       Keyword          Opt   Mode   Function
       -----------------------------------------------------------------
       via                           Specify  DNS  name  of mailserver,
                                     overriding poll name
       proto[col]       -p           Specify  protocol  (case  insensi-
                                     tive):  POP2,  POP3,  IMAP,  APOP,
                                     KPOP
       local[domains]         m      Specify domain(s) to  be  regarded
                                     as local
       port                          Specify TCP/IP service port (obso-
                                     lete, use 'service' instead).
       service          -P           Specify service  name  (a  numeric
                                     value  is also allowed and consid-
                                     ered a TCP/IP port number).
       auth[enticate]                Set authentication  type  (default
                                     'any')
       timeout          -t           Server  inactivity timeout in sec-
                                     onds (default 300)
       envelope         -E    m      Specify  envelope-address   header
                                     name
       no envelope            m      Disable   looking   for   envelope
                                     address
       qvirtual         -Q    m      Qmail  virtual  domain  prefix  to
                                     remove from user name
       aka                    m      Specify  alternate  DNS  names  of
                                     mailserver
       interface        -I           specify IP interface(s) that  must
                                     be  up  for  server  poll  to take
                                     place
       monitor          -M           Specify IP address to monitor  for
                                     activity
       plugin                        Specify  command  through which to
                                     make server connections.
       plugout                       Specify command through  which  to
                                     make listener connections.
       dns                    m      Enable  DNS  lookup  for multidrop
                                     (default)
       no dns                 m      Disable DNS lookup for multidrop

       checkalias             m      Do comparison by  IP  address  for
                                     multidrop
       no checkalias          m      Do  comparison  by  name  for mul-
                                     tidrop (default)
       uidl             -U           Force  POP3  to  use   client-side
                                     UIDLs (recommended)
       no uidl                       Turn  off  POP3 use of client-side
                                     UIDLs (default)
       interval                      Only check this site every N  poll
                                     cycles; N is a numeric argument.
       tracepolls                    Add  poll  tracing  information to
                                     the Received header
       principal                     Set Kerberos principal (only  use-
                                     ful with IMAP and kerberos)
       esmtpname                     Set  name  for RFC2554 authentica-
                                     tion to the ESMTP server.
       esmtppassword                 Set password for RFC2554 authenti-
                                     cation to the ESMTP server.
       bad-header                    How  to  treat messages with a bad
                                     header. Can be reject (default) or
                                     accept.

       Here are the legal user descriptions and options:


       Keyword            Opt       Mode   Function
       -----------------------------------------------------------------------
       user[name]         -u               This  is  the user description and
                                           must  come  first   after   server
                                           description   and  after  possible
                                           server options,  and  before  user
                                           options.

                                           It sets the remote user name if by
                                           itself or followed by 'there',  or
                                           the local user name if followed by
                                           'here'.
       is                                  Connect  local  and  remote   user
                                           names
       to                                  Connect   local  and  remote  user
                                           names
       pass[word]                          Specify remote account password
       ssl                                 Connect to server over the  speci-
                                           fied   base   protocol  using  SSL
                                           encryption
       sslcert                             Specify file for client side  pub-
                                           lic SSL certificate
       sslcertck                           Enable strict certificate checking
                                           and abort connection  on  failure.
                                           Default   only   since   fetchmail
                                           v6.4.0.
       no sslcertck                        Disable strict certificate  check-
                                           ing and permit connections to con-
                                           tinue on failed verification. Dis-
                                           couraged.   Should  only  be  used
                                           together with sslfingerprint.
       sslcertfile                         Specify file with trusted CA  cer-
                                           tificates
       sslcertpath                         Specify c_rehash-ed directory with
                                           trusted CA certificates.
       sslfingerprint     <HASH>           Specify the expected  server  cer-
                                           tificate  finger print from an MD5
                                           hash.  Fetchmail  will  disconnect
                                           and  log  an  error if it does not
                                           match.

       sslkey                              Specify file for client side  pri-
                                           vate SSL key
       sslproto                            Force ssl protocol for connection
       folder             -r               Specify remote folder to query
       smtphost           -S               Specify smtp host(s) to forward to
       fetchdomains                 m      Specify  domains  for  which  mail
                                           should be fetched
       smtpaddress        -D               Specify the domain to  be  put  in
                                           RCPT TO lines
       smtpname                            Specify  the user and domain to be
                                           put in RCPT TO lines
       antispam           -Z               Specify  what  SMTP  returns   are
                                           interpreted as spam-policy blocks
       mda                -m               Specify MDA for local delivery
       bsmtp                               Specify BSMTP batch file to append
                                           to
       preconnect                          Command to be executed before each
                                           connection
       postconnect                         Command  to be executed after each
                                           connection
       keep               -k               Don't delete  seen  messages  from
                                           server  (for  POP3, uidl is recom-
                                           mended)
       flush              -F               Flush  all  seen  messages  before
                                           querying (DANGEROUS)
       limitflush                          Flush   all   oversized   messages
                                           before querying
       fetchall           -a               Fetch all messages whether seen or
                                           not
       rewrite                             Rewrite  destination addresses for
                                           reply (default)
       stripcr                             Strip carriage returns  from  ends
                                           of lines
       forcecr                             Force  carriage returns at ends of
                                           lines
       pass8bits                           Force BODY=8BITMIME to ESMTP  lis-
                                           tener
       dropstatus                          Strip  Status and X-Mozilla-Status
                                           lines out of incoming mail
       dropdelivered                       Strip Delivered-To  lines  out  of
                                           incoming mail
       mimedecode                          Convert  quoted-printable to 8-bit
                                           in MIME messages
       idle                                Idle  waiting  for  new   messages
                                           after each poll (IMAP only)
       no keep            -K               Delete  seen  messages from server
                                           (default)
       no flush                            Don't  flush  all  seen   messages
                                           before querying (default)
       no fetchall                         Retrieve    only    new   messages
                                           (default)
       no rewrite                          Don't rewrite headers
       no stripcr                          Don't   strip   carriage   returns
                                           (default)
       no forcecr                          Don't  force  carriage  returns at
                                           EOL (default)
       no pass8bits                        Don't force BODY=8BITMIME to ESMTP
                                           listener (default)
       no dropstatus                       Don't    drop    Status    headers
                                           (default)
       no dropdelivered                    Don't  drop  Delivered-To  headers
                                           (default)
       no mimedecode                       Don't  convert quoted-printable to
                                           8-bit in MIME messages (default)


       no idle                             Don't idle waiting  for  new  mes-
                                           sages after each poll (IMAP only)
       limit              -l               Set message size limit
       warnings           -w               Set message size warning interval
       batchlimit         -b               Max  # messages to forward in sin-
                                           gle connect
       fetchlimit         -B               Max # messages to fetch in  single
                                           connect
       fetchsizelimit                      Max  #  message  sizes to fetch in
                                           single transaction
       fastuidl                            Use binary search for first unseen
                                           message (POP3 only)
       expunge            -e               Perform  an  expunge  on every #th
                                           message (IMAP and POP3 only)
       properties                          String value is ignored by  fetch-
                                           mail  (may  be  used  by extension
                                           scripts)

       All user options must begin with a user description (user  or  username
       option) and follow all server descriptions and options.

       In  the  .fetchmailrc  file, the 'envelope' string argument may be pre-
       ceded by a whitespace-separated number.  This number, if specified,  is
       the  number  of  such  headers  to skip over (that is, an argument of 1
       selects the second header of the given type).  This is sometime  useful
       for  ignoring bogus envelope headers created by an ISP's local delivery
       agent or  internal  forwards  (through  mail  inspection  systems,  for
       instance).

   Keywords Not Corresponding To Option Switches
       The  'folder' and 'smtphost' options (unlike their command-line equiva-
       lents) can take a space- or comma-separated  list  of  names  following
       them.

       All  options  correspond  to the obvious command-line arguments, except
       the following: 'via', 'interval', 'aka', 'is',  'to',  'dns'/'no  dns',
       'checkalias'/'no  checkalias', 'password', 'preconnect', 'postconnect',
       'localdomains',   'stripcr'/'no   stripcr',   'forcecr'/'no   forcecr',
       'pass8bits'/'no   pass8bits'  'dropstatus/no  dropstatus',  'dropdeliv-
       ered/no dropdelivered', 'mimedecode/no mimedecode', 'no idle', and  'no
       envelope'.

       The 'via' option is for if you want to have more than one configuration
       pointing at the same site.  If it is present, the string argument  will
       be  taken as the actual DNS name of the mailserver host to query.  This
       will override the argument of poll, which can then simply be a distinct
       label  for  the  configuration (e.g. what you would give on the command
       line to explicitly query this host).

       The 'interval' option (which takes a numeric argument)  allows  you  to
       poll a server less frequently than the basic poll interval.  If you say
       'interval N' the server this option is attached to will only be queried
       every N poll intervals.

   Singledrop vs. Multidrop options
       Please  ensure  you  read  the section titled THE USE AND ABUSE OF MUL-
       TIDROP MAILBOXES if you intend to use multidrop mode.

       The 'is' or  'to'  keywords  associate  the  following  local  (client)
       name(s)  (or  server-name  to client-name mappings separated by =) with
       the mailserver user name in the entry.  If an is/to list has '*' as its
       last  name,  unrecognized  names  are  simply passed through. Note that
       until fetchmail version 6.3.4 inclusively, these lists could only  con-
       tain  local  parts of user names (fetchmail would only look at the part
       before the @ sign). fetchmail versions 6.3.5  and  newer  support  full
       addresses on the left hand side of these mappings, and they take prece-
       dence over any 'localdomains', 'aka', 'via' or similar mappings.

       A single local name can be used to support redirecting your  mail  when
       your  username on the client machine is different from your name on the
       mailserver.  When there is only a single local name, mail is  forwarded
       to  that  local  username regardless of the message's Received, To, Cc,
       and Bcc headers.  In this case, fetchmail never does DNS lookups.

       When there is more than one local name  (or  name  mapping),  fetchmail
       looks  at  the  envelope  header,  if  configured, and otherwise at the
       Received, To, Cc, and Bcc headers of retrieved mail (this is 'multidrop
       mode').   It  looks  for  addresses with hostname parts that match your
       poll name or your 'via', 'aka' or 'localdomains' options,  and  usually
       also  for  hostname  parts  which  DNS  tells  it  are  aliases  of the
       mailserver.  See the discussion of 'dns', 'checkalias', 'localdomains',
       and 'aka' for details on how matching addresses are handled.

       If  fetchmail  cannot  match  any  mailserver  usernames or localdomain
       addresses, the mail will be bounced.  Normally it will  be  bounced  to
       the sender, but if the 'bouncemail' global option is off, the mail will
       go to the local  postmaster  instead.   (see  the  'postmaster'  global
       option). See also BUGS.

       The  'dns'  option  (normally  on) controls the way addresses from mul-
       tidrop mailboxes are checked.  On, it enables logic to check each  host
       address  that  does not match an 'aka' or 'localdomains' declaration by
       looking it up with DNS.   When  a  mailserver  username  is  recognized
       attached to a matching hostname part, its local mapping is added to the
       list of local recipients.

       The 'checkalias' option (normally off) extends the lookups performed by
       the  'dns'  keyword  in  multidrop  mode,  providing a way to cope with
       remote MTAs that identify themselves using their canonical name,  while
       they're polled using an alias.  When such a server is polled, checks to
       extract the envelope address fail, and fetchmail  reverts  to  delivery
       using   the   To/Cc/Bcc   headers   (See  below  'Header  vs.  Envelope
       addresses').  Specifying this option instructs  fetchmail  to  retrieve
       all  the  IP  addresses associated with both the poll name and the name
       used by the remote MTA and to do a  comparison  of  the  IP  addresses.
       This  comes  in  handy  in situations where the remote server undergoes
       frequent canonical name changes, that would otherwise require modifica-
       tions  to the rcfile.  'checkalias' has no effect if 'no dns' is speci-
       fied in the rcfile.

       The 'aka' option is for use with multidrop mailboxes.  It allows you to
       pre-declare  a  list of DNS aliases for a server.  This is an optimiza-
       tion hack that allows you to trade space for  speed.   When  fetchmail,
       while  processing  a multidrop mailbox, grovels through message headers
       looking for names of the mailserver, pre-declaring common ones can save
       it  from  having  to do DNS lookups.  Note: the names you give as argu-
       ments to 'aka' are matched as suffixes -- if  you  specify  (say)  'aka
       netaxs.com',  this  will  match not just a hostname netaxs.com, but any
       hostname that ends with '.netaxs.com'; such  as  (say)  pop3.netaxs.com
       and mail.netaxs.com.

       The 'localdomains' option allows you to declare a list of domains which
       fetchmail should consider local.  When  fetchmail  is  parsing  address
       lines in multidrop modes, and a trailing segment of a host name matches
       a declared local domain, that address is passed through to the listener
       or MDA unaltered (local-name mappings are not applied).

       If you are using 'localdomains', you may also need to specify 'no enve-
       lope', which disables fetchmail's normal attempt to deduce an  envelope
       address  from  the  Received  line  or X-Envelope-To header or whatever
       header has been previously set by 'envelope'.  If you set 'no envelope'
       in the defaults entry it is possible to undo that in individual entries
       by using 'envelope <string>'.  As a special case, 'envelope "Received"'
       restores the default parsing of Received lines.

       The  password  option requires a string argument, which is the password
       to be used with the entry's server.

       The 'preconnect' keyword allows you to specify a shell  command  to  be
       executed  just before each time fetchmail establishes a mailserver con-
       nection.  This may be useful if you are attempting to set up secure POP
       connections  with  the aid of ssh(1).  If the command returns a nonzero
       status, the poll of that mailserver will be aborted.

       Similarly, the 'postconnect' keyword similarly allows you to specify  a
       shell  command to be executed just after each time a mailserver connec-
       tion is taken down.

       The 'forcecr' option controls whether lines terminated by LF  only  are
       given  CRLF  termination  before  forwarding.  Strictly speaking RFC821
       requires this, but few MTAs enforce the requirement so this  option  is
       normally  off  (only one such MTA, qmail, is in significant use at time
       of writing).

       The 'stripcr' option controls whether carriage returns are stripped out
       of retrieved mail before it is forwarded.  It is normally not necessary
       to set this, because it defaults to 'on' (CR  stripping  enabled)  when
       there  is  an  MDA declared but 'off' (CR stripping disabled) when for-
       warding is via SMTP.  If 'stripcr' and 'forcecr' are both on, 'stripcr'
       will override.

       The 'pass8bits' option exists to cope with Microsoft mail programs that
       stupidly slap a "Content-Transfer-Encoding: 7bit" on everything.   With
       this  option  off  (the  default)  and such a header present, fetchmail
       declares BODY=7BIT to an ESMTP-capable listener; this  causes  problems
       for  messages  actually  using 8-bit ISO or KOI-8 character sets, which
       will be garbled by having the high bits of all characters stripped.  If
       'pass8bits'  is on, fetchmail is forced to declare BODY=8BITMIME to any
       ESMTP-capable listener.  If the listener is  8-bit-clean  (as  all  the
       major ones now are) the right thing will probably result.

       The 'dropstatus' option controls whether nonempty Status and X-Mozilla-
       Status lines are retained in fetched mail (the default)  or  discarded.
       Retaining  them  allows  your  MUA  to  see what messages (if any) were
       marked seen on the server.  On the other hand, it can confuse some new-
       mail notifiers, which assume that anything with a Status line in it has
       been seen.  (Note: the empty Status lines inserted by  some  buggy  POP
       servers are unconditionally discarded.)

       The  'dropdelivered'  option controls whether Delivered-To headers will
       be kept in fetched mail (the default) or discarded. These  headers  are
       added by Qmail and Postfix mailservers in order to avoid mail loops but
       may get in your way if you try to "mirror" a mailserver within the same
       domain. Use with caution.

       The  'mimedecode'  option  controls  whether  MIME  messages  using the
       quoted-printable encoding are automatically converted into  pure  8-bit
       data.  If you are delivering mail to an ESMTP-capable, 8-bit-clean lis-
       tener (that includes all of the major MTAs like  sendmail),  then  this
       will  automatically  convert  quoted-printable message headers and data
       into 8-bit data, making it easier to understand when reading  mail.  If
       your  e-mail  programs  know  how to deal with MIME messages, then this
       option is not needed.  The mimedecode option is off by default, because
       doing  RFC2047 conversion on headers throws away character-set informa-
       tion and can lead to bad results if the encoding of the headers differs
       from the body encoding.

       The  'idle'  option is intended to be used with IMAP servers supporting
       the RFC2177 IDLE command extension, but does not strictly  require  it.
       If it is enabled, and fetchmail detects that IDLE is supported, an IDLE
       will be issued at the end of each poll.  This will tell the IMAP server
       to  hold  the  connection  open  and notify the client when new mail is
       available.  If IDLE is not supported, fetchmail  will  simulate  it  by
       periodically  issuing NOOP. If you need to poll a link frequently, IDLE
       can save bandwidth by  eliminating  TCP/IP  connects  and  LOGIN/LOGOUT
       sequences. On the other hand, an IDLE connection will eat almost all of
       your fetchmail's time, because it will never drop  the  connection  and
       allow  other  polls  to occur unless the server times out the IDLE.  It
       also doesn't work with multiple folders; only  the  first  folder  will
       ever be polled.

       The  'properties'  option is an extension mechanism.  It takes a string
       argument, which is ignored by fetchmail itself.   The  string  argument
       may  be  used  to  store  configuration  information  for scripts which
       require it.  In particular, the output of  '--configdump'  option  will
       make  properties  associated  with  a user entry readily available to a
       Python script.

   Miscellaneous Run Control Options
       The words 'here' and 'there'  have  useful  English-like  significance.
       Normally  'user  eric  is esr' would mean that mail for the remote user
       'eric' is to be delivered to 'esr', but you can make  this  clearer  by
       saying 'user eric there is esr here', or reverse it by saying 'user esr
       here is eric there'

       Legal protocol identifiers for use with the 'protocol' keyword are:

           auto (or AUTO) (legacy, to be removed from future release)
           pop2 (or POP2) (legacy, to be removed from future release)
           pop3 (or POP3)
           sdps (or SDPS)
           imap (or IMAP)
           apop (or APOP)
           kpop (or KPOP)


       Legal authentication types are  'any',  'password',  'kerberos',  'ker-
       beros_v4',  'kerberos_v5'  and 'gssapi', 'cram-md5', 'otp', 'msn' (only
       for POP3), 'ntlm', 'ssh', 'external' (only IMAP).  The 'password'  type
       specifies  authentication  by  normal  transmission  of a password (the
       password may be plain text or subject to  protocol-specific  encryption
       as  in  CRAM-MD5);  'kerberos' tells fetchmail to try to get a Kerberos
       ticket at the start of each query instead, and send an arbitrary string
       as the password; and 'gssapi' tells fetchmail to use GSSAPI authentica-
       tion.  See the description of the 'auth' keyword for more.

       Specifying 'kpop' sets POP3 protocol over port 1109  with  Kerberos  V4
       authentication.  These defaults may be overridden by later options.

       There  are  some  global option statements: 'set logfile' followed by a
       string sets the same global specified  by  --logfile.   A  command-line
       --logfile option will override this. Note that --logfile is only effec-
       tive if fetchmail detaches itself from the  terminal  and  the  logfile
       already  exists  before  fetchmail is run, and it overrides --syslog in
       this case.  Also, 'set daemon' sets the poll interval as --daemon does.
       This can be overridden by a command-line --daemon option; in particular
       --daemon 0 can be used to force foreground operation. The 'set postmas-
       ter'  statement  sets  the  address to which multidrop mail defaults if
       there are no local matches.  Finally, 'set syslog' sends  log  messages
       to syslogd(8).


DEBUGGING FETCHMAIL
   Fetchmail crashing
       There are various ways in that fetchmail may "crash", i. e. stop opera-
       tion suddenly and unexpectedly. A "crash" usually refers  to  an  error
       condition  that  the  software  did  not handle by itself. A well-known
       failure mode is the "segmentation fault" or "signal 11" or "SIGSEGV" or
       just  "segfault" for short. These can be caused by hardware or by soft-
       ware problems. Software-induced segfaults  can  usually  be  reproduced
       easily and in the same place, whereas hardware-induced segfaults can go
       away if the computer is rebooted, or powered off for a few  hours,  and
       can  happen  in  random locations even if you use the software the same
       way.

       For solving hardware-induced segfaults, find the faulty  component  and
       repair  or replace it.  The Sig11 FAQ <https://www.bitwizard.nl/sig11/>
       may help you with details.

       For solving software-induced  segfaults,  the  developers  may  need  a
       "stack backtrace".


   Enabling fetchmail core dumps
       By  default,  fetchmail  suppresses  core  dumps as these might contain
       passwords and other  sensitive  information.  For  debugging  fetchmail
       crashes,  obtaining  a  "stack backtrace" from a core dump is often the
       quickest way to solve the problem, and when posting your problem  on  a
       mailing list, the developers may ask you for a "backtrace".

       1.  To  get  useful backtraces, fetchmail needs to be installed without
       getting stripped  of  its  compilation  symbols.   Unfortunately,  most
       binary  packages  that  are installed are stripped, and core files from
       symbol-stripped programs are worthless. So you may  need  to  recompile
       fetchmail. On many systems, you can type

               file `which fetchmail`

       to  find  out  if  fetchmail  was  symbol-stripped or not. If yours was
       unstripped, fine, proceed, if it was stripped, you  need  to  recompile
       the  source code first. You do not usually need to install fetchmail in
       order to debug it.

       2. The shell environment that starts fetchmail  needs  to  enable  core
       dumps.  The  key  is the "maximum core (file) size" that can usually be
       configured with a tool named "limit" or "ulimit". See the documentation
       for  your  shell  for  details.  In the popular bash shell, "ulimit -Sc
       unlimited" will allow the core dump.

       3. You need to tell fetchmail, too, to allow core dumps.  To  do  this,
       run  fetchmail with the -d0 -v options.  It is often easier to also add
       --nosyslog -N as well.

       Finally, you need to reproduce the crash. You can just start  fetchmail
       from  the directory where you compiled it by typing ./fetchmail, so the
       complete command line will start with ./fetchmail -Nvd0 --nosyslog  and
       perhaps list your other options.

       After the crash, run your debugger to obtain the core dump.  The debug-
       ger will often be GNU GDB, you can then type (adjust  paths  as  neces-
       sary) gdb ./fetchmail fetchmail.core and then, after GDB has started up
       and read all its files, type backtrace full, save the  output  (copy  &
       paste  will  do,  the  backtrace will be read by a human) and then type
       quit to leave gdb.  Note: on some systems, the core files have  differ-
       ent  names, they might contain a number instead of the program name, or
       number and name, but it will usually have "core" as part of their name.


INTERACTION WITH RFC 822
       When trying to determine the originating address of a  message,  fetch-
       mail looks through headers in the following order:

               Return-Path:
               Resent-Sender: (ignored if it doesn't contain an @ or !)
               Sender: (ignored if it doesn't contain an @ or !)
               Resent-From:
               From:
               Reply-To:
               Apparently-From:

       The  originating  address is used for logging, and to set the MAIL FROM
       address when forwarding to SMTP.  This order is intended to cope grace-
       fully  with  receiving  mailing  list  messages  in multidrop mode. The
       intent is that if a local address doesn't  exist,  the  bounce  message
       won't  be  returned  blindly  to  the author or to the list itself, but
       rather to the list manager (which is less annoying).

       In multidrop mode, destination headers are processed as follows: First,
       fetchmail  looks  for  the header specified by the 'envelope' option in
       order to  determine  the  local  recipient  address.  If  the  mail  is
       addressed  to  more than one recipient, the Received line won't contain
       any information regarding recipient addresses.

       Then fetchmail looks for the Resent-To:,  Resent-Cc:,  and  Resent-Bcc:
       lines.   If  they  exist,  they should contain the final recipients and
       have precedence over their To:/Cc:/Bcc: counterparts.  If the  Resent-*
       lines  don't  exist,  the  To:,  Cc:, Bcc: and Apparently-To: lines are
       looked for. (The presence of a Resent-To: is taken to  imply  that  the
       person  referred  by  the To: address has already received the original
       copy of the mail.)


CONFIGURATION EXAMPLES
       Note that although there are password declarations in a  good  many  of
       the  examples below, this is mainly for illustrative purposes.  We rec-
       ommend stashing account/password pairs in your $HOME/.netrc file, where
       they  can  be  used  not just by fetchmail but by ftp(1) and other pro-
       grams.

       The basic format is:


              poll SERVERNAME protocol PROTOCOL username NAME  password  PASS-
              WORD


       Example:


              poll pop.provider.net protocol pop3 username "jsmith" password "secret1"


       Or, using some abbreviations:


              poll pop.provider.net proto pop3 user "jsmith" password "secret1"


       Multiple servers may be listed:


              poll pop.provider.net proto pop3 user "jsmith" pass "secret1"
              poll other.provider.net proto pop2 user "John.Smith" pass "My^Hat"


       Here's the same version with more whitespace and some noise words:


              poll pop.provider.net proto pop3
                   user "jsmith", with password secret1, is "jsmith" here;
              poll other.provider.net proto pop2:
                   user "John.Smith", with password "My^Hat", is "John.Smith" here;


       If  you  need  to include whitespace in a parameter string or start the
       latter with a number, enclose the string in double quotes.  Thus:


              poll mail.provider.net with proto pop3:
                   user "jsmith" there has password "4u but u can't krak this"
                   is jws here and wants mda "/bin/mail"


       You may have an  initial  server  description  headed  by  the  keyword
       'defaults'  instead  of  'poll'  followed  by a name.  Such a record is
       interpreted as defaults for all queries to use. It may  be  overwritten
       by individual server descriptions.  So, you could write:


              defaults proto pop3
                   user "jsmith"
              poll pop.provider.net
                   pass "secret1"
              poll mail.provider.net
                   user "jjsmith" there has password "secret2"


       It's  possible  to  specify  more than one user per server.  The 'user'
       keyword leads off a user description, and every user specification in a
       multi-user entry must include it.  Here's an example:


              poll pop.provider.net proto pop3 port 3111
                   user "jsmith" with pass "secret1" is "smith" here
                   user jones with pass "secret2" is "jjones" here keep


       This  associates  the  local username 'smith' with the pop.provider.net
       username  'jsmith'  and  the   local   username   'jjones'   with   the
       pop.provider.net  username  'jones'.   Mail  for 'jones' is kept on the
       server after download.


       Here's what a simple retrieval configuration for  a  multidrop  mailbox
       looks like:


              poll pop.provider.net:
                   user maildrop with pass secret1 to golux 'hurkle'='happy' snark here


       This  says  that  the  mailbox of account 'maildrop' on the server is a
       multidrop box, and that messages in it should be parsed for the  server
       user  names  'golux', 'hurkle', and 'snark'.  It further specifies that
       'golux' and 'snark' have the same name on the client as on the  server,
       but  mail  for  server user 'hurkle' should be delivered to client user
       'happy'.


       Note  that  fetchmail,  until  version  6.3.4,  did  NOT   allow   full
       user@domain  specifications  here,  these would never match.  Fetchmail
       6.3.5 and newer support user@domain  specifications  on  the  left-hand
       side of a user mapping.


       Here's an example of another kind of multidrop connection:


              poll pop.provider.net localdomains loonytoons.org toons.org
                   envelope X-Envelope-To
                   user maildrop with pass secret1 to * here


       This  also says that the mailbox of account 'maildrop' on the server is
       a multidrop box.  It tells fetchmail that any  address  in  the  loony-
       toons.org  or  toons.org  domains  (including sub-domain addresses like
       'joe@daffy.loonytoons.org') should be passed through to the local  SMTP
       listener  without  modification.   Be  careful  of mail loops if you do
       this!


       Here's an example configuration using ssh and the plugin  option.   The
       queries  are  made  directly  on the stdin and stdout of imapd via ssh.
       Note that in this setup, IMAP authentication can be skipped.


              poll mailhost.net with proto imap:
                   plugin "ssh %h /usr/sbin/imapd" auth ssh;
                   user esr is esr here


THE USE AND ABUSE OF MULTIDROP MAILBOXES
       Use the multiple-local-recipients feature with caution -- it can  bite.
       All multidrop features are ineffective in ETRN and ODMR modes.

       Also, note that in multidrop mode duplicate mails may be suppressed.  A
       piece of mail is considered duplicate if it does not have a discernable
       envelope  recipient address, has the same header as the message immedi-
       ately preceding and more than one addressee.  Such runs of messages may
       be  generated  when copies of a message addressed to multiple users are
       delivered to a multidrop box. (To be precise, fetchmail  6.2.5  through
       6.4.X  use  an  MD5  hash of the raw message header, and only fetchmail
       6.4.16+ document this properly.  Fetchmail 5.0.8  (1999-09-14)  through
       6.2.4  used  only  the Message-ID header.  5.0.7 and older did not sup-
       press duplicates.)

       Note that this duplication killer code checking the  entire  header  is
       very restrictive and may not suppress many duplicates in practice - for
       instance, if some X-Original-To or Delivered-To header  differs.   This
       is intentional and correct in such situations: wherever envelope infor-
       mation is available, it should be used for reliable delivery of mailing
       list and blind carbon copy (Bcc) messages. See the subsection Duplicate
       suppression below for suggestions.


   Header vs. Envelope addresses
       The fundamental problem is that by having your mailserver toss  several
       peoples' mail in a single maildrop box, you may have thrown away poten-
       tially vital information about who each  piece  of  mail  was  actually
       addressed  to  (the  'envelope  address',  as  opposed  to  the  header
       addresses in the RFC822 To/Cc headers - the Bcc is not available at the
       receiving  end).   This  'envelope  address' is the address you need in
       order to reroute mail properly.

       Sometimes fetchmail can deduce the envelope address.  If the mailserver
       MTA  is  sendmail  and the item of mail had just one recipient, the MTA
       will have written a 'by/for' clause that gives the  envelope  addressee
       into  its  Received  header.  But  this doesn't work reliably for other
       MTAs, nor if there is more than one recipient.  By  default,  fetchmail
       looks  for  envelope  addresses  in  these  lines; you can restore this
       default with -E "Received" or 'envelope Received'.

       As a better alternative, some SMTP listeners and/or mail servers insert
       a  header  in each message containing a copy of the envelope addresses.
       This header (when it exists) is often  'X-Original-To',  'Delivered-To'
       or  'X-Envelope-To'.   Fetchmail's assumption about this can be changed
       with the -E or 'envelope' option.  Note that writing an envelope header
       of  this  kind  exposes  the  names of recipients (including blind-copy
       recipients) to all receivers of the  messages,  so  the  upstream  must
       store one copy of the message per recipient to avoid becoming a privacy
       problem.

       Postfix, since version 2.0, writes an X-Original-To: header which  con-
       tains a copy of the envelope as it was received.

       Qmail and Postfix generally write a 'Delivered-To' header upon deliver-
       ing the message to the mail spool and  use  it  to  avoid  mail  loops.
       Qmail  virtual  domains however will prefix the user name with a string
       that normally matches the user's domain. To remove this prefix you  can
       use the -Q or 'qvirtual' option.

       Sometimes,  unfortunately, neither of these methods works.  That is the
       point when you should contact your ISP and ask them to provide such  an
       envelope  header,  and  you should not use multidrop in this situation.
       When they all fail, fetchmail must fall back on the contents  of  To/Cc
       headers (Bcc headers are not available - see below) to try to determine
       recipient addressees -- and these are unreliable.  In particular, mail-
       ing-list software often ships mail with only the list broadcast address
       in the To header.

       Note that a future version of fetchmail may remove To/Cc parsing!

       When fetchmail cannot deduce a recipient address that is local, and the
       intended  recipient  address was anyone other than fetchmail's invoking
       user, mail will get lost.  This is what  makes  the  multidrop  feature
       risky without proper envelope information.

       A  related  problem is that when you blind-copy a mail message, the Bcc
       information is carried only as envelope address (it's removed from  the
       headers  by  the  sending  mail server, so fetchmail can see it only if
       there is an X-Envelope-To header).  Thus, blind-copying to someone  who
       gets  mail  over  a  fetchmail  multidrop link will fail unless the the
       mailserver host routinely writes X-Envelope-To or an equivalent  header
       into messages in your maildrop.

       In conclusion, mailing lists and Bcc'd mail can only work if the server
       you're fetching from

       (1)    stores one copy of the message per recipient in your domain and

       (2)    records the envelope information in a special  header  (X-Origi-
              nal-To, Delivered-To, X-Envelope-To).


   Good Ways To Use Multidrop Mailboxes
       Multiple  local names can be used to administer a mailing list from the
       client side of a fetchmail collection.  Suppose your name is 'esr', and
       you  want  to  both  pick  up your own mail and maintain a mailing list
       called (say) "fetchmail-friends", and you want to keep the  alias  list
       on your client machine.

       On  your  server,  you can alias 'fetchmail-friends' to 'esr'; then, in
       your .fetchmailrc, declare 'to esr fetchmail-friends here'.  Then, when
       mail including 'fetchmail-friends' as a local address gets fetched, the
       list name will be appended to the list of recipients your SMTP listener
       sees.   Therefore  it will undergo alias expansion locally.  Be sure to
       include 'esr' in the local alias  expansion  of  fetchmail-friends,  or
       you'll  never  see  mail sent only to the list.  Also be sure that your
       listener has the "me-too"  option  set  (sendmail's  -oXm  command-line
       option or OXm declaration) so your name isn't removed from alias expan-
       sions in messages you send.

       This trick is not without its problems, however.  You'll begin  to  see
       this  when  a message comes in that is addressed only to a mailing list
       you do not have declared as a local name.  Each such message will  fea-
       ture  an 'X-Fetchmail-Warning' header which is generated because fetch-
       mail cannot find a valid local name in the recipient  addresses.   Such
       messages  default  (as  was described above) to being sent to the local
       user running fetchmail, but the program has no way to know that  that's
       actually the right thing.


   Bad Ways To Abuse Multidrop Mailboxes
       Multidrop mailboxes and fetchmail serving multiple users in daemon mode
       do not mix.  The problem, again, is mail from mailing lists, which typ-
       ically  does  not  have an individual recipient address on it.   Unless
       fetchmail can deduce an envelope address, such mail will only go to the
       account  running  fetchmail  (probably root).  Also, blind-copied users
       are very likely never to see their mail at all.

       If you're tempted to use fetchmail to retrieve mail for multiple  users
       from  a  single  mail drop via POP or IMAP, think again (and reread the
       section on header and envelope addresses above).  It would  be  smarter
       to  just let the mail sit in the mailserver's queue and use fetchmail's
       ETRN or ODMR modes to trigger SMTP sends periodically (of course,  this
       means  you  have  to  poll more frequently than the mailserver's expiry
       period).  If you can't arrange this, try setting up a UUCP feed.

       If you absolutely must use multidrop for this purpose, make  sure  your
       mailserver  writes  an  envelope-address header that fetchmail can see.
       Otherwise you will lose mail and it will come back to haunt you.


   Speeding Up Multidrop Checking
       Normally, when multiple users are declared fetchmail extracts recipient
       addresses  as described above and checks each host part with DNS to see
       if it's an alias of the mailserver.  If so, the name mappings described
       in  the  "to ... here" declaration are done and the mail locally deliv-
       ered.

       This is a convenient but also slow method.  To speed it up, pre-declare
       mailserver aliases with 'aka'; these are checked before DNS lookups are
       done.  If you're certain your aka list contains all DNS aliases of  the
       mailserver (and all MX names pointing at it - note this may change in a
       future version) you can  declare  'no  dns'  to  suppress  DNS  lookups
       entirely and only match against the aka list.


   Duplicate suppression on multidrop
       If  fetchmail's  duplicate  suppression  code does not kick in for your
       multidrop mail account, other options is using sieve, or  for  instance
       Courier's  maildrop  package  (and in particular, its reformail program
       with the -D option) as the delivery agent (either  from  fetchmail,  or
       from your local mail server that fetchmail injects into).


SOCKS
       Support  for socks4/5 is a compile time configuration option. Once com-
       piled in, fetchmail will always use the socks libraries and  configura-
       tion  on your system, there are no run-time switches in fetchmail - but
       you can still configure SOCKS: you can specify which  SOCKS  configura-
       tion file is used in the SOCKS_CONF environment variable.

       For  instance,  if  you wanted to bypass the SOCKS proxy altogether and
       have   fetchmail   connect    directly,    you    could    just    pass
       SOCKS_CONF=/dev/null  in  the  environment, for example (add your usual
       command line options - if any - to the end of this line):

       env SOCKS_CONF=/dev/null fetchmail


EXIT CODES
       To facilitate the use of fetchmail in  shell  scripts,  an  exit status
       code  is returned to give an indication of what occurred during a given
       connection.

       The exit codes returned by fetchmail are as follows:

       0      One or more messages were successfully retrieved (or, if the  -c
              option was selected, were found waiting but not retrieved).

       1      There  was no mail awaiting retrieval.  (There may have been old
              mail still on the server but not selected for retrieval.) If you
              do  not  want  "no mail" to be an error condition (for instance,
              for cron jobs), use a POSIX-compliant shell and add

              || [ $? -eq 1 ]

              to the end of the fetchmail command line, note that this  leaves
              0  untouched,  maps  1  to 0, and maps all other codes to 1. See
              also item #C8 in the FAQ.

       2      An error was encountered when attempting to  open  a  socket  to
              retrieve  mail.  If you don't know what a socket is, don't worry
              about it -- just treat this as an 'unrecoverable  error'.   This
              error  can  also be because a protocol fetchmail wants to use is
              not listed in /etc/services.

       3      The user authentication step failed.  This usually means that  a
              bad user-id, password, or APOP id was specified.  Or it may mean
              that you tried to run fetchmail under circumstances where it did
              not  have  standard  input  attached to a terminal and could not
              prompt for a missing password.

       4      Some sort of fatal protocol error was detected.

       5      There was a syntax error in the arguments  to  fetchmail,  or  a
              pre- or post-connect command failed.

       6      The run control file had bad permissions.

       7      There  was  an error condition reported by the server.  Can also
              fire if fetchmail timed out while waiting for the server.

       8      Client-side exclusion error.  This means fetchmail either  found
              another  copy of itself already running, or failed in such a way
              that it isn't sure whether another copy is running.

       9      The user authentication step failed because the server responded
              "lock  busy".  Try again after a brief pause!  This error is not
              implemented for all protocols, nor  for  all  servers.   If  not
              implemented  for  your server, "3" will be returned instead, see
              above.  May be returned when talking to qpopper or other servers
              that  can respond with "lock busy" or some similar text contain-
              ing the word "lock".

       10     The fetchmail run failed while trying to do an SMTP port open or
              transaction.

       11     Fatal  DNS error.  Fetchmail encountered an error while perform-
              ing a DNS lookup at startup and could not proceed.

       12     BSMTP batch file could not be opened.

       13     Poll terminated by a fetch limit (see the --fetchlimit option).

       14     Server busy indication.

       23     Internal error.  You should see a message on standard error with
              details.

       24 - 26, 28, 29
              These are internal codes and should not appear externally.

       When  fetchmail  queries  more than one host, return status is 0 if any
       query successfully retrieved mail. Otherwise the returned error  status
       is that of the last host queried.


FILES
       ~/.fetchmailrc, $HOME/.fetchmailrc, $HOME_ETC/.fetchmailrc, $FETCHMAIL-
       HOME/fetchmailrc
            default run control file (location can be overridden with environ-
            ment variables)

       ~/.fetchids,    $HOME/.fetchids,    $HOME_ETC/.fetchids,    $FETCHMAIL-
       HOME/.fetchids
            default location of file recording  last  message  UIDs  seen  per
            host.  (location can be overridden with environment variables)

       ~/.fetchmail.pid,    $HOME/.fetchmail.pid,    $HOME_ETC/.fetchmail.pid,
       $FETCHMAILHOME/fetchmail.pid
            default location of lock file (sometimes  called  pidfile  or  PID
            file,  see  option  pidfile) to help prevent concurrent runs (non-
            root mode).  (location can be overridden  with  environment  vari-
            ables)

       ~/.netrc, $HOME/.netrc, $HOME_ETC/.netrc
            your FTP run control file, which (if present) will be searched for
            passwords as a last resort before prompting for one interactively.
            (location can be overridden with environment variables)

       /var/run/fetchmail.pid
            lock  file  (pidfile)  to help prevent concurrent runs (root mode,
            Linux systems).

       /etc/fetchmail.pid
            lock file (pidfile) to help prevent concurrent  runs  (root  mode,
            systems without /var/run).


ENVIRONMENT
       Fetchmail's  behavior  can  be altered by providing it with environment
       variables. Some may alter the operation  of  libraries  that  fetchmail
       links  against,  for  instance, OpenSSL.  Note that in daemon mode, you
       will need to quit the background daemon process and start a new  fetch-
       mail daemon for environment changes to take effect.

       FETCHMAILHOME
              If  this  environment  variable  is  set to a valid and existing
              directory name, fetchmail will  read  $FETCHMAILHOME/fetchmailrc
              (the  dot  is  missing  in  this case), $FETCHMAILHOME/.fetchids
              (keeping its dot) and $FETCHMAILHOME/fetchmail.pid (without dot)
              rather  than from the user's home directory.  The .netrc file is
              always looked for in the the invoking user's home directory  (or
              $HOME_ETC) regardless of FETCHMAILHOME's setting.


       FETCHMAILUSER
              If  this  environment variable is set, it is used as the name of
              the calling user (default local name) for purposes such as mail-
              ing  error  notifications.   Otherwise, if either the LOGNAME or
              USER variable is  correctly  set  (e.g.  the  corresponding  UID
              matches  the  session  user  ID)  then  that name is used as the
              default local name.   Otherwise  getpwuid(3)  must  be  able  to
              retrieve  a  password  entry  for the session ID (this elaborate
              logic is designed to handle  the  case  of  multiple  names  per
              userid gracefully).


       FETCHMAIL_DISABLE_CBC_IV_COUNTERMEASURE
              (since  v6.3.22):  If  this  environment variable is set and not
              empty, fetchmail will disable a countermeasure  against  an  SSL
              CBC  IV  attack (by setting SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS).
              This is a security risk, but may be necessary for connecting  to
              certain  non-standards-conforming servers.  See fetchmail's NEWS
              file and fetchmail-SA-2012-01.txt for details.   Earlier  fetch-
              mail  versions (v6.3.21 and older) used to disable this counter-
              measure, but v6.3.22 no longer does that as a safety precaution.


       FETCHMAIL_POP3_FORCE_RETR
              (since v6.3.9): If this environment variable is defined  at  all
              (even  if  empty), fetchmail will forgo the POP3 TOP command and
              always use RETR. This can be used as a workaround when TOP  does
              not work properly.


       FETCHMAIL_INCLUDE_DEFAULT_X509_CA_CERTS
              (since  v6.3.17):  If  this  environment variable is set and not
              empty, fetchmail will always load the default X.509 trusted cer-
              tificate   locations   for  SSL/TLS  CA  certificates,  even  if
              --sslcertfile and --sslcertpath are given.  The latter locations
              take precedence over the system default locations.  This is use-
              ful in case there are broken certificates in the system directo-
              ries  and the user has no administrator privileges to remedy the
              problem.


       HOME   (documented since 6.4.1): This variable is nomally  set  to  the
              user's  home  directory.  If  it is set to a different directory
              than what is in the password database, HOME takes precedence.


       HOME_ETC
              (documentation  corrected  to  match  behaviour  of  code  since
              6.4.1): If the HOME_ETC variable is set, it will override fetch-
              mail's idea of $HOME, i. e. fetchmail  will  read  .fetchmailrc,
              .fetchids,  .fetchmail.pid  and .netrc from $HOME_ETC instead of
              $HOME (or if HOME is also unset, from  the  passwd  file's  home
              directory location).

              If  HOME_ETC and FETCHMAILHOME are both set, FETCHMAILHOME takes
              prececence and HOME_ETC will be ignored.


       SOCKS_CONF
              (only if SOCKS support is compiled in) this variable is used  by
              the socks library to find out which configuration file it should
              read. Set this to /dev/null to bypass the SOCKS proxy.


       SSL_CERT_DIR
              (with  truly  OpenSSL  1.1.1  compatible   library):   overrides
              OpenSSL's  idea  of  the  default trust directory or path (which
              contains individual certificate files and hashed symlinks),  see
              the SSL_CTX_set_default_verify_paths(3) manual page for details,
              it may be in the openssl development package.  If using  another
              library's  OpenSSL  compatibility  interface, this may not work.
              Since this variable only specifies a default value,  the  option
              --sslcertpath takes precedence if given.


       SSL_CERT_FILE
              (with   truly   OpenSSL  1.1.1  compatible  library):  overrides
              OpenSSL's idea of the  default  trust  certificate  bundle  file
              (which  contains  a concatenation of base64-encoded certificates
              in PEM format), see the SSL_CTX_set_default_verify_paths(3) man-
              ual page for details, it may be in the openssl development pack-
              age.  If using another library's  OpenSSL  compatibility  inter-
              face,  this  may not work.  Since this variable only specifies a
              default value, the  option  --sslcertfile  takes  precedence  if
              given.


SIGNALS
       If  a fetchmail daemon is running as root, SIGUSR1 wakes it up from its
       sleep phase and forces a poll of all non-skipped servers. For  compati-
       bility  reasons, SIGHUP can also be used in 6.3.X but may not be avail-
       able in future fetchmail versions.

       If fetchmail is running in daemon mode as non-root, use SIGUSR1 to wake
       it  (this  is  so SIGHUP due to logout can retain the default action of
       killing it).

       Running fetchmail in foreground while a background fetchmail is running
       will do whichever of these is appropriate to wake it up.


BUGS, LIMITATIONS, AND KNOWN PROBLEMS
       Please  check  the NEWS file that shipped with fetchmail for more known
       bugs than those listed here.

       Fetchmail cannot handle user names that  contain  blanks  after  a  "@"
       character, for instance "demonstr@ti on". These are rather uncommon and
       only hurt when using UID-based --keep setups, so the 6.3.X versions  of
       fetchmail won't be fixed.

       Fetchmail cannot handle configurations where you have multiple accounts
       that use the same server name and the same login. Any user@server  com-
       bination must be unique.

       The  assumptions  that the DNS and in particular the checkalias options
       make are not often sustainable. For instance, it  has  become  uncommon
       for  an  MX server to be a POP3 or IMAP server at the same time. There-
       fore the MX lookups may go away in a future release.

       The mda and plugin options interact badly.  In order to  collect  error
       status from the MDA, fetchmail has to change its normal signal handling
       so that dead plugin processes don't get reaped until  the  end  of  the
       poll  cycle.   This  can  cause resource starvation if too many zombies
       accumulate.  So either don't deliver to a MDA  using  plugins  or  risk
       being overrun by an army of undead.

       The  --interface  option does not support IPv6 and it is doubtful if it
       ever will, since there is no  portable  way  to  query  interface  IPv6
       addresses.

       The  RFC822  address  parser  used  in  multidrop  mode  chokes on some
       @-addresses that are technically legal but bizarre.   Strange  uses  of
       quoting and embedded comments are likely to confuse it.

       In  a  message  with  multiple envelope headers, only the last one pro-
       cessed will be visible to fetchmail.

       Use of some of these protocols requires that  the  program  send  unen-
       crypted  passwords  over the TCP/IP connection to the mailserver.  This
       creates a risk that name/password pairs might be snaffled with a packet
       sniffer  or  more  sophisticated  monitoring software.  Under Linux and
       FreeBSD, the --interface option can be  used  to  restrict  polling  to
       availability  of  a  specific interface device with a specific local or
       remote IP address, but snooping is still possible if  (a)  either  host
       has a network device that can be opened in promiscuous mode, or (b) the
       intervening network link can be tapped.  We recommend the use of ssh(1)
       tunnelling  to  not  only  shroud your passwords but encrypt the entire
       conversation.

       Use of the %F or %T escapes in an mda  option  could  open  a  security
       hole, because they pass text manipulable by an attacker to a shell com-
       mand.  Potential shell characters are replaced by '_' before execution.
       The hole is further reduced by the fact that fetchmail temporarily dis-
       cards any suid privileges it may have while running the MDA.  For maxi-
       mum  safety, however, don't use an mda command containing %F or %T when
       fetchmail is run from the root account itself.

       Fetchmail's method of sending bounces due to  errors  or  spam-blocking
       and  spam  bounces  requires that port 25 of localhost be available for
       sending mail via SMTP.

       If you modify ~/.fetchmailrc while a background instance is running and
       break  the syntax, the background instance will die silently.  Unfortu-
       nately, it can't die noisily because we don't yet know  whether  syslog
       should  be  enabled.   On  some systems, fetchmail dies quietly even if
       there is no syntax error; this seems to have something to do with buggy
       terminal ioctl code in the kernel.

       The  -f  -  option (reading a configuration from stdin) is incompatible
       with the plugin option.

       The 'principal' option only handles Kerberos IV, not V.

       Interactively entered passwords are truncated after 63  characters.  If
       you  really  need to use a longer password, you will have to use a con-
       figuration file.

       A backslash as the last character  of  a  configuration  file  will  be
       flagged as a syntax error rather than ignored.

       The  BSMTP error handling is virtually nonexistent and may leave broken
       messages behind.

       Send comments, bug reports, gripes, and the like to the fetchmail-devel
       list <fetchmail-devel@lists.sourceforge.net>


       An  HTML  FAQ  <https://fetchmail.sourceforge.io/fetchmail-FAQ.html> is
       available at the fetchmail home page, it  should  also  accompany  your
       installation.


AUTHOR
       Fetchmail  is currently maintained by Matthias Andree and Rob Funk with
       major assistance from Sunil Shetye (for code) and  Rob  MacGregor  (for
       the mailing lists).

       Most of the code is from Eric S. Raymond <esr@snark.thyrsus.com> .  Too
       many other people to name here have contributed code and patches.

       This program is descended from and replaces popclient, by  Carl  Harris
       <ceharris@mal.com>  ;  the  internals  have become quite different, but
       some of its interface design is directly traceable  to  that  ancestral
       program.

       This  manual page has been improved by Matthias Andree, R. Hannes Bein-
       ert, and Hctor Garca.



ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+------------------+
       |ATTRIBUTE TYPE | ATTRIBUTE VALUE  |
       +---------------+------------------+
       |Availability   | mail/fetchmail   |
       +---------------+------------------+
       |Stability      | Committed        |
       +---------------+------------------+

SEE ALSO
       README, README.SSL, README.SSL-SERVER, The Fetchmail FAQ <https://
       www.fetchmail.info/fetchmail-FAQ.html>, mutt(1), elm(1), mail(1), send-
       mail(8), popd(8), imapd(8), netrc(5).

       The fetchmail home page.  <https://www.fetchmail.info/>

       The fetchmail home page (alternative URI).  <https://
       fetchmail.sourceforge.io/>

       The maildrop home page.  <https://www.courier-mta.org/maildrop/>

APPLICABLE STANDARDS
       Note that this list is just a collection of references and not a state-
       ment as to the actual protocol conformance or  requirements  in  fetch-
       mail.

       SMTP/ESMTP:
            RFC  821,  RFC  2821,  RFC 1869, RFC 1652, RFC 1870, RFC 1983, RFC
            1985, RFC 2554.

       mail:
            RFC 822, RFC 2822, RFC 1123, RFC 1892, RFC 1894.

       POP2:
            RFC 937

       POP3:
            RFC 1081, RFC 1225, RFC 1460, RFC 1725, RFC 1734,  RFC  1939,  RFC
            1957, RFC 2195, RFC 2449.

       APOP:
            RFC 1939.

       RPOP:
            RFC 1081, RFC 1225.

       IMAP2/IMAP2BIS:
            RFC 1176, RFC 1732.

       IMAP4/IMAP4rev1:
            RFC  1730,  RFC  1731, RFC 1732, RFC 2060, RFC 2061, RFC 2195, RFC
            2177, RFC 2683.

       ETRN:
            RFC 1985.

       ODMR/ATRN:
            RFC 2645.

       OTP: RFC 1938.

       LMTP:
            RFC 2033.

       GSSAPI:
            RFC 1508, RFC 1734, Generic Security Service Application Program
            Interface (GSSAPI)/Kerberos/Simple Authentication and Security
            Layer (SASL) Service Names <https://www.iana.org/assignments/
            gssapi-service-names/>.

       TLS: RFC 2595.



NOTES
       Source  code  for open source software components in Oracle Solaris can
       be found at https://www.oracle.com/downloads/opensource/solaris-source-
       code-downloads.html.

       This     software     was    built    from    source    available    at
       https://github.com/oracle/solaris-userland.   The  original   community
       source  was  downloaded  from   https://sourceforge.net/projects/fetch-
       mail/files/branch_6.4/fetchmail-6.4.22.tar.xz.

       Further information about this software can be found on the open source
       community website at http://www.fetchmail.info/.



fetchmail 6.4.22                  2021-08-10                      fetchmail(1)