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Updated: Thursday, June 13, 2019
 
 

oqmgr (8)

Name

oqmgr - old Postfix queue manager

Synopsis

oqmgr [generic Postfix daemon options]

Description

OQMGR(8)                    System Manager's Manual                   OQMGR(8)



NAME
       oqmgr - old Postfix queue manager

SYNOPSIS
       oqmgr [generic Postfix daemon options]

DESCRIPTION
       The  oqmgr(8)  daemon  awaits the arrival of incoming mail and arranges
       for its delivery via Postfix delivery processes.  The actual mail rout-
       ing  strategy is delegated to the trivial-rewrite(8) daemon.  This pro-
       gram expects to be run from the master(8) process manager.

       Mail addressed to the local double-bounce address is  logged  and  dis-
       carded.   This  stops  potential  loops  caused by undeliverable bounce
       notifications.

MAIL QUEUES
       The oqmgr(8) daemon maintains the following queues:

       incoming
              Inbound mail from the network, or mail picked up  by  the  local
              pickup(8) agent from the maildrop directory.

       active Messages  that the queue manager has opened for delivery. Only a
              limited number of messages is allowed to enter the active  queue
              (leaky bucket strategy, for a fixed delivery rate).

       deferred
              Mail  that  could  not  be delivered upon the first attempt. The
              queue manager implements exponential  backoff  by  doubling  the
              time between delivery attempts.

       corrupt
              Unreadable or damaged queue files are moved here for inspection.

       hold   Messages  that  are  kept  "on hold" are kept here until someone
              sets them free.

DELIVERY STATUS REPORTS
       The oqmgr(8) daemon keeps an eye on per-message delivery status reports
       in the following directories. Each status report file has the same name
       as the corresponding message file:

       bounce Per-recipient status information  about  why  mail  is  bounced.
              These files are maintained by the bounce(8) daemon.

       defer  Per-recipient  status  information  about  why  mail is delayed.
              These files are maintained by the defer(8) daemon.

       trace  Per-recipient status information as requested with  the  Postfix
              "sendmail  -v" or "sendmail -bv" command.  These files are main-
              tained by the trace(8) daemon.

       The oqmgr(8) daemon is responsible for asking the  bounce(8),  defer(8)
       or trace(8) daemons to send delivery reports.

STRATEGIES
       The queue manager implements a variety of strategies for either opening
       queue files (input) or for message delivery (output).

       leaky bucket
              This strategy limits the number of messages in the active  queue
              and  prevents the queue manager from running out of memory under
              heavy load.

       fairness
              When the active queue has room, the queue manager takes one mes-
              sage  from  the  incoming queue and one from the deferred queue.
              This prevents a large mail backlog from blocking the delivery of
              new mail.

       slow start
              This  strategy  eliminates  "thundering herd" problems by slowly
              adjusting the number of parallel deliveries to the same destina-
              tion.

       round robin
              The  queue  manager  sorts  delivery  requests  by  destination.
              Round-robin selection prevents one destination  from  dominating
              deliveries to other destinations.

       exponential backoff
              Mail  that  cannot  be  delivered  upon  the  first  attempt  is
              deferred.  The time interval between delivery attempts  is  dou-
              bled after each attempt.

       destination status cache
              The  queue manager avoids unnecessary delivery attempts by main-
              taining a short-term, in-memory  list  of  unreachable  destina-
              tions.

TRIGGERS
       On  an  idle system, the queue manager waits for the arrival of trigger
       events, or it waits for a timer to go off. A trigger is a one-byte mes-
       sage.   Depending  on  the message received, the queue manager performs
       one of the following actions (the message is followed by  the  symbolic
       constant used internally by the software):

       D (QMGR_REQ_SCAN_DEFERRED)
              Start  a  deferred  queue  scan.   If  a  deferred queue scan is
              already in progress, that scan will be restarted as soon  as  it
              finishes.

       I (QMGR_REQ_SCAN_INCOMING)
              Start  an  incoming  queue  scan.  If  an incoming queue scan is
              already in progress, that scan will be restarted as soon  as  it
              finishes.

       A (QMGR_REQ_SCAN_ALL)
              Ignore  deferred queue file time stamps. The request affects the
              next deferred queue scan.

       F (QMGR_REQ_FLUSH_DEAD)
              Purge all information about dead transports and destinations.

       W (TRIGGER_REQ_WAKEUP)
              Wakeup call, This is used by the master  server  to  instantiate
              servers  that should not go away forever. The action is to start
              an incoming queue scan.

       The oqmgr(8) daemon reads an entire buffer worth of triggers.  Multiple
       identical trigger requests are collapsed into one, and trigger requests
       are sorted so that A and F precede D and I. Thus, in order to  force  a
       deferred  queue  run,  one  would request A F D; in order to notify the
       queue manager of the arrival of new mail one would request I.

STANDARDS
       RFC 3463 (Enhanced status codes)
       RFC 3464 (Delivery status notifications)

SECURITY
       The oqmgr(8) daemon is not security sensitive. It reads  single-charac-
       ter messages from untrusted local users, and thus may be susceptible to
       denial of service attacks. The oqmgr(8) daemon does  not  talk  to  the
       outside  world,  and it can be run at fixed low privilege in a chrooted
       environment.

DIAGNOSTICS
       Problems and transactions are logged to  the  syslog(8)  daemon.   Cor-
       rupted message files are saved to the corrupt queue for further inspec-
       tion.

       Depending on the setting of the notify_classes parameter, the  postmas-
       ter is notified of bounces and of other trouble.

BUGS
       A single queue manager process has to compete for disk access with mul-
       tiple front-end processes such as cleanup(8). A sudden burst of inbound
       mail can negatively impact outbound delivery rates.

CONFIGURATION PARAMETERS
       Changes  to  main.cf  are not picked up automatically, as oqmgr(8) is a
       persistent process. Use the command "postfix reload" after a configura-
       tion change.

       The  text  below provides only a parameter summary. See postconf(5) for
       more details including examples.

       In the text below, transport is the first field in a master.cf entry.

COMPATIBILITY CONTROLS
       Available before Postfix version 2.5:

       allow_min_user (no)
              Allow a sender or recipient address to have  `-'  as  the  first
              character.

       Available with Postfix version 2.7 and later:

       default_filter_nexthop (empty)
              When  a  content_filter  or FILTER request specifies no explicit
              next-hop destination, use $default_filter_nexthop instead;  when
              that value is empty, use the domain in the recipient address.

ACTIVE QUEUE CONTROLS
       qmgr_clog_warn_time (300s)
              The  minimal  delay between warnings that a specific destination
              is clogging up the Postfix active queue.

       qmgr_message_active_limit (20000)
              The maximal number of messages in the active queue.

       qmgr_message_recipient_limit (20000)
              The maximal number of recipients held in memory by  the  Postfix
              queue manager, and the maximal size of the short-term, in-memory
              "dead" destination status cache.

DELIVERY CONCURRENCY CONTROLS
       qmgr_fudge_factor (100)
              Obsolete feature: the percentage of delivery  resources  that  a
              busy  mail  system  will  use up for delivery of a large mailing
              list message.

       initial_destination_concurrency (5)
              The  initial  per-destination  concurrency  level  for  parallel
              delivery to the same destination.

       default_destination_concurrency_limit (20)
              The  default  maximal  number of parallel deliveries to the same
              destination.

       transport_destination_concurrency_limit   ($default_destination_concur-
       rency_limit)
              Idem, for delivery via the named message transport.

       Available in Postfix version 2.5 and later:

       transport_initial_destination_concurrency ($initial_destination_concur-
       rency)
              Initial concurrency for delivery via the  named  message  trans-
              port.

       default_destination_concurrency_failed_cohort_limit (1)
              How  many  pseudo-cohorts  must  suffer  connection or handshake
              failure before a specific destination is considered  unavailable
              (and further delivery is suspended).

       transport_destination_concurrency_failed_cohort_limit  ($default_desti-
       nation_concurrency_failed_cohort_limit)
              Idem, for delivery via the named message transport.

       default_destination_concurrency_negative_feedback (1)
              The per-destination  amount  of  delivery  concurrency  negative
              feedback,  after a delivery completes with a connection or hand-
              shake failure.

       transport_destination_concurrency_negative_feedback  ($default_destina-
       tion_concurrency_negative_feedback)
              Idem, for delivery via the named message transport.

       default_destination_concurrency_positive_feedback (1)
              The  per-destination  amount  of  delivery  concurrency positive
              feedback, after a delivery completes without connection or hand-
              shake failure.

       transport_destination_concurrency_positive_feedback  ($default_destina-
       tion_concurrency_positive_feedback)
              Idem, for delivery via the named message transport.

       destination_concurrency_feedback_debug (no)
              Make the queue manager's feedback algorithm verbose for  perfor-
              mance analysis purposes.

RECIPIENT SCHEDULING CONTROLS
       default_destination_recipient_limit (50)
              The default maximal number of recipients per message delivery.

       transport_destination_recipient_limit
              Idem, for delivery via the named message transport.

OTHER RESOURCE AND RATE CONTROLS
       minimal_backoff_time (300s)
              The minimal time between attempts to deliver a deferred message;
              prior to Postfix 2.4 the default value was 1000s.

       maximal_backoff_time (4000s)
              The maximal time between attempts to deliver a deferred message.

       maximal_queue_lifetime (5d)
              Consider a message as undeliverable, when delivery fails with  a
              temporary error, and the time in the queue has reached the maxi-
              mal_queue_lifetime limit.

       queue_run_delay (300s)
              The time between deferred queue  scans  by  the  queue  manager;
              prior to Postfix 2.4 the default value was 1000s.

       transport_retry_time (60s)
              The  time  between attempts by the Postfix queue manager to con-
              tact a malfunctioning message delivery transport.

       Available in Postfix version 2.1 and later:

       bounce_queue_lifetime (5d)
              Consider a bounce message as undeliverable, when delivery  fails
              with  a  temporary  error, and the time in the queue has reached
              the bounce_queue_lifetime limit.

       Available in Postfix version 2.5 and later:

       default_destination_rate_delay (0s)
              The default amount of delay that is inserted between  individual
              deliveries  to  the  same  destination;  the  resulting behavior
              depends on the value of the corresponding per-destination recip-
              ient limit.

       transport_destination_rate_delay $default_destination_rate_delay
              Idem, for delivery via the named message transport.

       Available in Postfix version 3.1 and later:

       default_transport_rate_delay (0s)
              The  default amount of delay that is inserted between individual
              deliveries over the same message delivery transport,  regardless
              of destination.

       transport_transport_rate_delay $default_transport_rate_delay
              Idem, for delivery via the named message transport.

SAFETY CONTROLS
       qmgr_daemon_timeout (1000s)
              How much time a Postfix queue manager process may take to handle
              a request before it is terminated by a built-in watchdog timer.

       qmgr_ipc_timeout (60s)
              The time limit for the queue manager to send or receive informa-
              tion over an internal communication channel.

       Available in Postfix version 3.1 and later:

       address_verify_pending_request_limit (see 'postconf -d' output)
              A  safety limit that prevents address verification requests from
              overwhelming the Postfix queue.

MISCELLANEOUS CONTROLS
       config_directory (see 'postconf -d' output)
              The default location of the Postfix main.cf and  master.cf  con-
              figuration files.

       defer_transports (empty)
              The names of message delivery transports that should not deliver
              mail unless someone issues "sendmail -q" or equivalent.

       delay_logging_resolution_limit (2)
              The maximal number of digits after the decimal point  when  log-
              ging sub-second delay values.

       helpful_warnings (yes)
              Log  warnings about problematic configuration settings, and pro-
              vide helpful suggestions.

       process_id (read-only)
              The process ID of a Postfix command or daemon process.

       process_name (read-only)
              The process name of a Postfix command or daemon process.

       queue_directory (see 'postconf -d' output)
              The location of the Postfix top-level queue directory.

       syslog_facility (mail)
              The syslog facility of Postfix logging.

       syslog_name (see 'postconf -d' output)
              A prefix that  is  prepended  to  the  process  name  in  syslog
              records, so that, for example, "smtpd" becomes "prefix/smtpd".

       Available in Postfix version 3.0 and later:

       confirm_delay_cleared (no)
              After  sending  a "your message is delayed" notification, inform
              the sender when the delay clears up.

FILES
       /var/spool/postfix/incoming, incoming queue
       /var/spool/postfix/active, active queue
       /var/spool/postfix/deferred, deferred queue
       /var/spool/postfix/bounce, non-delivery status
       /var/spool/postfix/defer, non-delivery status
       /var/spool/postfix/trace, delivery status


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


       +---------------+------------------------------+
       |ATTRIBUTE TYPE |       ATTRIBUTE VALUE        |
       +---------------+------------------------------+
       |Availability   | service/network/smtp/postfix |
       +---------------+------------------------------+
       |Stability      | Volatile                     |
       +---------------+------------------------------+
SEE ALSO
       trivial-rewrite(8), address routing
       bounce(8), delivery status reports
       postconf(5), configuration parameters
       master(5), generic daemon options
       master(8), process manager
       syslogd(8), system logging

README FILES
       Use "postconf readme_directory" or "postconf html_directory" to  locate
       this information.
       QSHAPE_README, Postfix queue analysis

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.



                                                                      OQMGR(8)