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.

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 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)
	      The maximal time a message is queued before it is sent  back  as
	      undeliverable.

       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)
	      The maximal time a bounce message is queued before it is consid-
	      ered undeliverable.

       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; with per-destination recipi-
	      ent limit > 1, a destination is a	 domain,  otherwise  it	 is  a
	      recipient.

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

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.

       ipc_timeout (3600s)
	      The  time	 limit	for  sending  or receiving information over an
	      internal communication channel.

       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, "post-
	      fix/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(8)