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  pro-
       cesses.   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  direc-
              tory.

       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" com-
              mand.  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 deliver-
              ies to the same destination.

       round robin
              The queue manager sorts delivery requests by desti-
              nation.   Round-robin selection prevents one desti-
              nation from dominating deliveries to other destina-
              tions.

       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 for-
              ever. The action is  to  start  an  incoming  queue
              scan.

       The  oqmgr(8) daemon reads an entire buffer worth of trig-
       gers.  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  environ-
       ment.

DIAGNOSTICS
       Problems and transactions are logged to the syslog(8) dae-
       mon.  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  trou-
       ble.

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 mas-
       ter.cf entry.

COMPATIBILITY CONTROLS
       allow_min_user (no)
              Allow a 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" desti-
              nation 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
              Idem, for delivery via the named message transport.

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

       transport_destination_recipient_limit
              Idem, for delivery via the named message transport.

OTHER RESOURCE AND RATE CONTROLS
       minimal_backoff_time (version dependent)
              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 undeliverable.

       queue_run_delay (version dependent)
              The  time between deferred queue scans by the queue
              manager.

       transport_retry_time (60s)
              The time between attempts by the Postfix queue man-
              ager  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.

MISCELLANEOUS CONTROLS
       config_directory (see 'postconf -d' output)
              The  default  location  of  the Postfix main.cf and
              master.cf 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  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 set-
              tings, 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 (see 'postconf -d' output)
              The  location of the Postfix top-level queue direc-
              tory.

       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, "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
       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)