Provided by: postfix_2.2.10-1_i386 bug


       oqmgr - old Postfix queue manager


       oqmgr [generic Postfix daemon options]


       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


       The oqmgr(8) daemon maintains the following queues:

              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).

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

              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.


       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.


       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.

              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

       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


       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):

              Start a deferred queue  scan.   If  a  deferred  queue  scan  is
              already  in  progress, that scan will be restarted as soon as it

              Start an incoming queue scan.  If  an  incoming  queue  scan  is
              already  in  progress, that scan will be restarted as soon as it

              Ignore deferred queue file time stamps. The request affects  the
              next deferred queue scan.

              Purge all information about dead transports and destinations.

              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.


       None. The oqmgr(8) daemon does not interact with the outside world.


       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.


       Problems   and   transactions  are  logged  to  the  syslog(8)  daemon.
       Corrupted message files are saved to  the  corrupt  queue  for  further

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


       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.


       Changes to 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 entry.


       allow_min_user (no)
              Allow a recipient address to have ‘-’ as the first character.


       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.


       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

              Idem, for delivery via the named message transport.


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

              Idem, for delivery via the named message transport.


       minimal_backoff_time (1000s)
              The minimal time between attempts to deliver a deferred message.

       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

       queue_run_delay (1000s)
              The time between deferred queue scans by the queue manager.

       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.


       config_directory (seepostconf -doutput)
              The  default  location  of  the  Postfix  and
              configuration files.

       daemon_timeout (18000s)
              How much time a Postfix daemon process  may  take  to  handle  a
              request before it is terminated by a built-in watchdog timer.

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

       helpful_warnings (yes)
              Log  warnings  about  problematic  configuration  settings,  and
              provide 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 (seepostconf -doutput)
              The location of the Postfix top-level queue directory.

       syslog_facility (mail)
              The syslog facility of Postfix logging.

       syslog_name (postfix)
              The  mail  system  name that is prepended to the process name in
              syslog  records,  so  that   "smtpd"   becomes,   for   example,


       /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


       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


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


       The Secure Mailer license must be distributed with this software.


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