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OQMGR(8)                                                                                            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 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  mail-drop maildrop
              drop 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 exponen-tial exponential
              tial 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  inter-nally internally
       nally 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 com-mand command
       mand "postfix reload" after a configuration change.

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

       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 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 destina-tion destination
              tion is considered unavailable (and further delivery is suspended).

       transport_destination_concurrency_failed_cohort_limit                   ($default_destination_concur-rency_failed_cohort_limit) ($default_destination_concurrency_failed_cohort_limit)
       rency_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  com-pletes completes
              pletes with a connection or handshake failure.

       transport_destination_concurrency_negative_feedback  ($default_destination_concurrency_negative_feed-back) ($default_destination_concurrency_negative_feedback)
       back)
              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 com-pletes completes
              pletes without connection or handshake failure.

       transport_destination_concurrency_positive_feedback  ($default_destination_concurrency_positive_feed-back) ($default_destination_concurrency_positive_feedback)
       back)
              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)
              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  contact  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 considered 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 desti-nation; destination;
              nation; with per-destination recipient 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.

SAFETY CONTROLS
       qmgr_daemon_timeout (1000s)
              How much time a Postfix queue manager process may take to handle a request before it is termi-nated terminated
              nated 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  communi-cation communication
              cation 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(8)