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>> qmgr (8) ( Linux man: Команды системного администрирования )
Postfix queue manager
qmgr [generic Postfix daemon options]
The qmgr(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
This program expects to be run from the master(8) process
Mail addressed to the local double-bounce address is
logged and discarded. This stops potential loops caused by
undeliverable bounce notifications.
The qmgr(8) daemon maintains the following queues:
Inbound mail from the network, or mail picked up by the
local pickup(8) daemon from the maildrop directory.
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
Unreadable or damaged queue files are moved here for inspection.
Messages that are kept "on hold" are kept here until someone
sets them free.
DELIVERY STATUS REPORTS
The qmgr(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:
Per-recipient status information about why mail is bounced.
These files are maintained by the bounce(8) daemon.
Per-recipient status information about why mail is delayed.
These files are maintained by the defer(8) daemon.
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 qmgr(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).
This strategy limits the number of messages in the active queue
and prevents the queue manager from running out of memory under
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.
This strategy eliminates "thundering herd" problems by slowly
adjusting the number of parallel deliveries to the same destination.
The queue manager sorts delivery requests by destination.
Round-robin selection prevents one destination from dominating
deliveries to other destinations.
Mail that cannot be delivered upon the first attempt is deferred.
The time interval between delivery attempts is doubled after each
destination status cache
The queue manager avoids unnecessary delivery attempts by
maintaining a short-term, in-memory list of unreachable destinations.
preemptive message scheduling
The queue manager attempts to minimize the average per-recipient delay
while still preserving the correct per-message delays, using
a sophisticated preemptive message scheduling.
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 finishes.
Start an incoming queue scan. If an incoming queue scan is already
in progress, that scan will be restarted as soon as it finishes.
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 qmgr(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.
RFC 3463 (Enhanced status codes)
RFC 3464 (Delivery status notifications)
The qmgr(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 qmgr(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 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.
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 main.cf are not picked up automatically
is a persistent process. Use the "postfix reload" command 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
Allow a recipient address to have `-' as the first character.
ACTIVE QUEUE CONTROLS
The minimal delay between warnings that a specific destination is
clogging up the Postfix active queue.
The maximal number of messages in the active queue.
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.
The minimal number of in-memory recipients for any message.
The default per-transport upper limit on the number of in-memory
Idem, for delivery via the named message transport.
OTHER RESOURCE AND RATE CONTROLS
The minimal time between attempts to deliver a deferred message.
The maximal time between attempts to deliver a deferred message.
The maximal time a message is queued before it is sent back as
The time between deferred queue scans by the queue manager.
The time between attempts by the Postfix queue manager to contact
a malfunctioning message delivery transport.
Available in Postfix version 2.1 and later:
The maximal time a bounce message is queued before it is considered
config_directory (see 'postconf -d' output)
The default location of the Postfix main.cf and master.cf
How much time a Postfix daemon process may take to handle a
request before it is terminated by a built-in watchdog timer.
The names of message delivery transports that should not deliver mail
unless someone issues "sendmail -q" or equivalent.
The maximal number of digits after the decimal point when logging
sub-second delay values.
Log warnings about problematic configuration settings, and provide
The time limit for sending or receiving information over an internal
The process ID of a Postfix command or daemon process.
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.
The syslog facility of Postfix logging.
The mail system name that is prepended to the process name in syslog
records, so that "smtpd" becomes, for example, "postfix/smtpd".
/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