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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
       routing  strategy  is delegated to the trivial-rewrite(8) daemon.  This
       program expects to be run from the master(8) process manager.

       Mail addressed  to  the  local  double-bounce  address  is  logged  and
       discarded.   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
              maintained 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
              message 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
              destination.

       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
              doubled after each attempt.

       destination status cache
              The  queue  manager  avoids  unnecessary  delivery  attempts  by
              maintaining  a  short-term,  in-memory   list   of   unreachable
              destinations.

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
       message.  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-
       character  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.
       Corrupted  message  files  are  saved  to the corrupt queue for further
       inspection.

       Depending  on  the  setting  of  the  notify_classes   parameter,   the
       postmaster is notified of bounces and of other trouble.

BUGS

       A  single  queue  manager  process  has to compete for disk access with
       multiple 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
       configuration 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_concurrency_limit)
              Idem, for delivery via the named message transport.

       Available in Postfix version 2.5 and later:

       transport_initial_destination_concurrency
       ($initial_destination_concurrency)
              Initial  concurrency  for  delivery  via   the   named   message
              transport.

       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_destination_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
              handshake failure.

       transport_destination_concurrency_negative_feedback
       ($default_destination_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
              handshake failure.

       transport_destination_concurrency_positive_feedback
       ($default_destination_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
              performance 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
              maximal_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
              contact 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
              recipient limit.

       transport_destination_rate_delay $default_destination_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
              information over an internal communication channel.

MISCELLANEOUS CONTROLS

       config_directory (see 'postconf -d' output)
              The  default  location  of  the  Postfix  main.cf  and master.cf
              configuration 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
              logging sub-second delay values.

       helpful_warnings (yes)
              Log  warnings  about  problematic  configuration  settings,  and
              provide 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)
              The  mail  system  name that is prepended to the process name in
              syslog  records,  so  that   "smtpd"   becomes,   for   example,
              "postfix/smtpd".

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

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

                                                               OQMGR(8postfix)



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