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man pages section 5: File Formats

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Updated: Thursday, June 13, 2019
 
 

virtual (5)

Name

virtual - Postfix virtual alias table format

Synopsis

postmap /etc/postfix/virtual

postmap -q "string" /etc/postfix/virtual

postmap -q - /etc/postfix/virtual <inputfile

Description

VIRTUAL(5)                    File Formats Manual                   VIRTUAL(5)



NAME
       virtual - Postfix virtual alias table format

SYNOPSIS
       postmap /etc/postfix/virtual

       postmap -q "string" /etc/postfix/virtual

       postmap -q - /etc/postfix/virtual <inputfile

DESCRIPTION
       The  optional  virtual(5)  alias table rewrites recipient addresses for
       all local, all virtual, and all  remote  mail  destinations.   This  is
       unlike  the  aliases(5) table which is used only for local(8) delivery.
       Virtual aliasing is  recursive,  and  is  implemented  by  the  Postfix
       cleanup(8) daemon before mail is queued.

       The main applications of virtual aliasing are:

       o      To redirect mail for one address to one or more addresses.

       o      To  implement  virtual  alias  domains  where  all addresses are
              aliased to addresses in other domains.

              Virtual alias domains are not to be confused  with  the  virtual
              mailbox domains that are implemented with the Postfix virtual(8)
              mail delivery agent. With virtual mailbox domains, each  recipi-
              ent address can have its own mailbox.

       Virtual  aliasing  is applied only to recipient envelope addresses, and
       does not affect message headers.  Use canonical(5) mapping  to  rewrite
       header and envelope addresses in general.

       Normally,  the  virtual(5) alias table is specified as a text file that
       serves as input to the postmap(1) command.  The result, an indexed file
       in  dbm  or  db  format, is used for fast searching by the mail system.
       Execute  the  command  "postmap  /etc/postfix/virtual"  to  rebuild  an
       indexed file after changing the corresponding text file.

       When  the  table  is provided via other means such as NIS, LDAP or SQL,
       the same lookups are done as for ordinary indexed files.

       Alternatively, the table can be provided as  a  regular-expression  map
       where  patterns  are  given  as  regular expressions, or lookups can be
       directed to TCP-based server. In those case, the lookups are done in  a
       slightly  different  way  as  described below under "REGULAR EXPRESSION
       TABLES" or "TCP-BASED TABLES".

CASE FOLDING
       The search string is folded to lowercase before database lookup. As  of
       Postfix  2.3,  the search string is not case folded with database types
       such as regexp: or pcre: whose lookup fields can match both  upper  and
       lower case.

TABLE FORMAT
       The input format for the postmap(1) command is as follows:

       pattern address, address, ...
              When  pattern  matches  a mail address, replace it by the corre-
              sponding address.

       blank lines and comments
              Empty lines and whitespace-only lines are ignored, as are  lines
              whose first non-whitespace character is a `#'.

       multi-line text
              A  logical  line  starts  with  non-whitespace text. A line that
              starts with whitespace continues a logical line.

TABLE SEARCH ORDER
       With lookups from indexed files such as DB or DBM,  or  from  networked
       tables  such  as  NIS,  LDAP  or SQL, each user@domain query produces a
       sequence of query patterns as described below.

       Each query pattern is sent to each specified lookup table before trying
       the next query pattern, until a match is found.

       user@domain address, address, ...
              Redirect  mail  for  user@domain  to address.  This form has the
              highest precedence.

       user address, address, ...
              Redirect mail for user@site to address when  site  is  equal  to
              $myorigin,  when site is listed in $mydestination, or when it is
              listed in $inet_interfaces or $proxy_interfaces.

              This functionality overlaps  with  functionality  of  the  local
              aliases(5)  database.  The difference is that virtual(5) mapping
              can be applied to non-local addresses.

       @domain address, address, ...
              Redirect mail for other users in domain to address.   This  form
              has the lowest precedence.

              Note:  @domain  is a wild-card. With this form, the Postfix SMTP
              server accepts mail for any recipient in domain,  regardless  of
              whether  that  recipient exists.  This may turn your mail system
              into a  backscatter  source:  Postfix  first  accepts  mail  for
              non-existent  recipients  and  then tries to return that mail as
              "undeliverable" to the often forged sender address.

RESULT ADDRESS REWRITING
       The lookup result is subject to address rewriting:

       o      When the result has the form @otherdomain,  the  result  becomes
              the  same  user  in  otherdomain.  This works only for the first
              address in a multi-address lookup result.

       o      When "append_at_myorigin=yes", append "@$myorigin" to  addresses
              without "@domain".

       o      When "append_dot_mydomain=yes", append ".$mydomain" to addresses
              without ".domain".

ADDRESS EXTENSION
       When a mail address localpart contains the optional recipient delimiter
       (e.g.,  user+foo@domain),  the  lookup  order becomes: user+foo@domain,
       user@domain, user+foo, user, and @domain.

       The  propagate_unmatched_extensions  parameter  controls   whether   an
       unmatched address extension (+foo) is propagated to the result of table
       lookup.

VIRTUAL ALIAS DOMAINS
       Besides virtual aliases, the virtual alias table can also  be  used  to
       implement  virtual  alias  domains.  With  a  virtual alias domain, all
       recipient addresses are aliased to addresses in other domains.

       Virtual alias domains are not to be confused with the  virtual  mailbox
       domains  that are implemented with the Postfix virtual(8) mail delivery
       agent. With virtual mailbox domains, each recipient  address  can  have
       its own mailbox.

       With  a  virtual alias domain, the virtual domain has its own user name
       space. Local (i.e. non-virtual) usernames are not visible in a  virtual
       alias  domain.  In particular, local aliases(5) and local mailing lists
       are not visible as localname@virtual-alias.domain.

       Support for a virtual alias domain looks like:

       /etc/postfix/main.cf:
           virtual_alias_maps = hash:/etc/postfix/virtual

       Note: some systems use dbm databases instead of hash.  See  the  output
       from "postconf -m" for available database types.

       /etc/postfix/virtual:
           virtual-alias.domain    anything (right-hand content does not matter)
           postmaster@virtual-alias.domain postmaster
           user1@virtual-alias.domain      address1
           user2@virtual-alias.domain      address2, address3

       The virtual-alias.domain anything entry is required for a virtual alias
       domain. Without  this  entry,  mail  is  rejected  with  "relay  access
       denied", or bounces with "mail loops back to myself".

       Do  not specify virtual alias domain names in the main.cf mydestination
       or relay_domains configuration parameters.

       With a virtual alias domain, the Postfix SMTP server accepts  mail  for
       known-user@virtual-alias.domain, and rejects mail for unknown-user@vir-
       tual-alias.domain as undeliverable.

       Instead of specifying the  virtual  alias  domain  name  via  the  vir-
       tual_alias_maps  table,  you  may  also specify it via the main.cf vir-
       tual_alias_domains configuration parameter.  This latter parameter uses
       the same syntax as the main.cf mydestination configuration parameter.

REGULAR EXPRESSION TABLES
       This  section  describes how the table lookups change when the table is
       given in the form of regular expressions. For a description of  regular
       expression lookup table syntax, see regexp_table(5) or pcre_table(5).

       Each  pattern  is  a  regular  expression that is applied to the entire
       address being looked up. Thus, user@domain mail addresses are not  bro-
       ken  up  into their user and @domain constituent parts, nor is user+foo
       broken up into user and foo.

       Patterns are applied in the order as specified in the  table,  until  a
       pattern is found that matches the search string.

       Results  are the same as with indexed file lookups, with the additional
       feature that parenthesized substrings from the pattern can be  interpo-
       lated as $1, $2 and so on.

TCP-BASED TABLES
       This  section  describes  how the table lookups change when lookups are
       directed  to  a  TCP-based  server.  For  a  description  of  the   TCP
       client/server  lookup  protocol, see tcp_table(5).  This feature is not
       available up to and including Postfix version 2.4.

       Each lookup operation uses the entire address once.  Thus,  user@domain
       mail  addresses  are  not  broken  up  into their user and @domain con-
       stituent parts, nor is user+foo broken up into user and foo.

       Results are the same as with indexed file lookups.

BUGS
       The table format does not understand quoting conventions.

CONFIGURATION PARAMETERS
       The following main.cf parameters are especially relevant to this topic.
       See the Postfix main.cf file for syntax details and for default values.
       Use the "postfix reload" command after a configuration change.

       virtual_alias_maps
              List of virtual aliasing tables.

       virtual_alias_domains
              List of virtual alias domains. This uses the same syntax as  the
              mydestination parameter.

       propagate_unmatched_extensions
              A list of address rewriting or forwarding mechanisms that propa-
              gate an address extension  from  the  original  address  to  the
              result.  Specify zero or more of canonical, virtual, alias, for-
              ward, include, or generic.

       Other parameters of interest:

       inet_interfaces
              The network interface addresses that this system  receives  mail
              on.   You  need  to  stop  and start Postfix when this parameter
              changes.

       mydestination
              List of domains that this mail system considers local.

       myorigin
              The domain that is appended to any address that does not have  a
              domain.

       owner_request_special
              Give special treatment to owner-xxx and xxx-request addresses.

       proxy_interfaces
              Other  interfaces that this machine receives mail on by way of a
              proxy agent or network address translator.


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


       +---------------+------------------------------+
       |ATTRIBUTE TYPE |       ATTRIBUTE VALUE        |
       +---------------+------------------------------+
       |Availability   | service/network/smtp/postfix |
       +---------------+------------------------------+
       |Stability      | Volatile                     |
       +---------------+------------------------------+
SEE ALSO
       cleanup(8), canonicalize and enqueue mail
       postmap(1), Postfix lookup table manager
       postconf(5), configuration parameters
       canonical(5), canonical address mapping

README FILES
       Use "postconf readme_directory" or "postconf html_directory" to  locate
       this information.
       ADDRESS_REWRITING_README, address rewriting guide
       DATABASE_README, Postfix lookup table overview
       VIRTUAL_README, domain hosting guide

LICENSE
       The Secure Mailer license must be distributed with this software.

AUTHOR(S)
       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       Yorktown Heights, NY 10598, USA

       Wietse Venema
       Google, Inc.
       111 8th Avenue
       New York, NY 10011, USA



NOTES
       This software was built from source available at
       https://github.com/oracle/solaris-userland.  The original community
       source was downloaded from  https://archive.mgm51.com/mirrors/postfix-
       source/official/postfix-3.2.2.tar.gz

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



                                                                    VIRTUAL(5)