Manual Pages for UNIX Darwin command on man qmgr

QMGR(8) QMGR(8)

NAME

qmgr - Postfix queue manager

SYNOPSIS

qqmmggrr [generic Postfix daemon options]

DESCRIPTION

The qqmmggrr 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 ttrriivviiaall-rreewwrriittee(8) daemon. This program

expects to be run from the mmaasstteerr(8) process manager.

Mail addressed to the local ddoouubbllee-bboouunnccee address is logged and dis-

carded. This stops potential loops caused by undeliverable bounce notifications. MMAAIILL QQUUEEUUEESS The qqmmggrr daemon maintains the following queues: iinnccoommiinngg Inbound mail from the network, or mail picked up by the local ppiicckkuupp agent from the mmaaiillddrroopp directory. aaccttiivvee Messages that the queue manager has opened for delivery. Only a limited number of messages is allowed to enter the aaccttiivvee queue (leaky bucket strategy, for a fixed delivery rate). ddeeffeerrrreedd Mail that could not be delivered upon the first attempt. The queue manager implements exponential backoff by doubling the time between delivery attempts. ccoorrrruupptt Unreadable or damaged queue files are moved here for inspection. hhoolldd Messages that are kept "on hold" are kept here until someone sets them free. DDEELLIIVVEERRYY SSTTAATTUUSS RREEPPOORRTTSS

The qqmmggrr 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:

bboouunnccee Per-recipient status information about why mail is bounced.

These files are maintained by the bboouunnccee(8) daemon.

ddeeffeerr Per-recipient status information about why mail is delayed.

These files are maintained by the ddeeffeerr(8) daemon.

ttrraaccee Per-recipient status information as requested with the Postfix

"sseennddmmaaiill -vv" or "sseennddmmaaiill -bbvv" command. These files are main-

tained by the ttrraaccee(8) daemon. The qqmmggrr daemon is responsible for asking the bboouunnccee(8), ddeeffeerr(8) or ttrraaccee(8) daemons to send delivery reports. SSTTRRAATTEEGGIIEESS The queue manager implements a variety of strategies for either opening queue files (input) or for message delivery (output). lleeaakkyy bbuucckkeett This strategy limits the number of messages in the aaccttiivvee queue and prevents the queue manager from running out of memory under heavy load. ffaaiirrnneessss

When the aaccttiivvee queue has room, the queue manager takes one mes-

sage from the iinnccoommiinngg queue and one from the ddeeffeerrrreedd queue. This prevents a large mail backlog from blocking the delivery of new mail. ssllooww ssttaarrtt This strategy eliminates "thundering herd" problems by slowly

adjusting the number of parallel deliveries to the same destina-

tion. rroouunndd rroobbiinn The queue manager sorts delivery requests by destination.

Round-robin selection prevents one destination from dominating

deliveries to other destinations. eexxppoonneennttiiaall bbaacckkooffff Mail that cannot be delivered upon the first attempt is

deferred. The time interval between delivery attempts is dou-

bled after each attempt. ddeessttiinnaattiioonn ssttaattuuss ccaacchhee

The queue manager avoids unnecessary delivery attempts by main-

taining a short-term, in-memory list of unreachable destina-

tions. pprreeeemmppttiivvee mmeessssaaggee sscchheedduulliinngg

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. TTRRIIGGGGEERRSS 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): DD ((QQMMGGRRRREEQQSSCCAANNDDEEFFEERRRREEDD)) Start a deferred queue scan. If a deferred queue scan is already in progress, that scan will be restarted as soon as it finishes. II ((QQMMGGRRRREEQQSSCCAANNIINNCCOOMMIINNGG)) Start an incoming queue scan. If an incoming queue scan is already in progress, that scan will be restarted as soon as it finishes. AA ((QQMMGGRRRREEQQSSCCAANNAALLLL)) Ignore deferred queue file time stamps. The request affects the next deferred queue scan. FF ((QQMMGGRRRREEQQFFLLUUSSHHDDEEAADD)) Purge all information about dead transports and destinations. WW ((TTRRIIGGGGEERRRREEQQWWAAKKEEUUPP)) 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 qqmmggrr daemon reads an entire buffer worth of triggers. Multiple identical trigger requests are collapsed into one, and trigger requests are sorted so that AA and FF precede DD and II. Thus, in order to force a deferred queue run, one would request AA FF DD; in order to notify the queue manager of the arrival of new mail one would request II. STANDARDS None. The qqmmggrr daemon does not interact with the outside world. SSEECCUURRIITTYY

The qqmmggrr 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 qqmmggrr 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 daemon. Corrupted message files are saved to the ccoorrrruupptt queue for further inspection.

Depending on the setting of the nnoottiiffyyccllaasssseess 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 ssmmttppdd. A sudden burst of inbound mail

can negatively impact outbound delivery rates. CCOONNFFIIGGUURRAATTIIOONN PPAARRAAMMEETTEERRSS

Changes to mmaaiinn..ccff are not picked up automatically as qmgr(8) processes

are persistent. Use the ppoossttffiixx rreellooaadd 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 mmaasstteerr..ccff entry. CCOOMMPPAATTIIBBIILLIITTYY CCOONNTTRROOLLSS aalllloowwmmiinnuusseerr ((nnoo))

Allow a recipient address to have `-' as the first character.

AACCTTIIVVEE QQUUEEUUEE CCOONNTTRROOLLSS qqmmggrrccllooggwwaarrnnttiimmee ((330000ss)) The minimal delay between warnings that a specific destination is clogging up the Postfix active queue. qqmmggrrmmeessssaaggeeaaccttiivveelliimmiitt ((2200000000)) The maximal number of messages in the active queue. qqmmggrrmmeessssaaggeerreecciippiieennttlliimmiitt ((2200000000)) 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.

qqmmggrrmmeessssaaggeerreecciippiieennttmmiinniimmuumm ((1100))

The minimal number of in-memory recipients for any message.

ddeeffaauullttrreecciippiieennttlliimmiitt ((1100000000))

The default per-transport upper limit on the number of in-memory

recipients.

transportrreecciippiieennttlliimmiitt (($$ddeeffaauullttrreecciippiieennttlliimmiitt))

Idem, for delivery via the named message transport. ddeeffaauulltteexxttrraarreecciippiieennttlliimmiitt ((11000000))

The default value for the extra per-transport limit imposed on

the number of in-memory recipients.

transporteexxttrraarreecciippiieennttlliimmiitt (($$ddeeffaauulltteexxttrraarreecciippiieennttlliimmiitt))

Idem, for delivery via the named message transport. DDEELLIIVVEERRYY CCOONNCCUURRRREENNCCYY CCOONNTTRROOLLSS iinniittiiaallddeessttiinnaattiioonnccoonnccuurrrreennccyy ((55))

The initial per-destination concurrency level for parallel

delivery to the same destination. ddeeffaauullttddeessttiinnaattiioonnccoonnccuurrrreennccyylliimmiitt ((2200)) The default maximal number of parallel deliveries to the same destination.

transportddeessttiinnaattiioonnccoonnccuurrrreennccyylliimmiitt (($$ddeeffaauullttddeessttiinnaattiioonnccoonnccuurr-

rreennccyylliimmiitt)) Idem, for delivery via the named message transport. RREECCIIPPIIEENNTT SSCCHHEEDDUULLIINNGG CCOONNTTRROOLLSS ddeeffaauullttddeessttiinnaattiioonnrreecciippiieennttlliimmiitt ((5500)) The default maximal number of recipients per message delivery.

transportddeessttiinnaattiioonnrreecciippiieennttlliimmiitt (($$ddeeffaauullttddeessttiinnaattiioonnrreecciippii-

eennttlliimmiitt)) Idem, for delivery via the named message transport. MMEESSSSAAGGEE SSCCHHEEDDUULLIINNGG CCOONNTTRROOLLSS ddeeffaauullttddeelliivveerryysslloottccoosstt ((55)) How often the Postfix queue manager's scheduler is allowed to preempt delivery of one message with another.

transportddeelliivveerryysslloottccoosstt (($$ddeeffaauullttddeelliivveerryysslloottccoosstt))

Idem, for delivery via the named message transport. ddeeffaauullttmmiinniimmuummddeelliivveerryysslloottss ((33)) How many recipients a message must have in order to invoke the Postfix queue manager's scheduling algorithm at all.

transportmmiinniimmuummddeelliivveerryysslloottss (($$ddeeffaauullttmmiinniimmuummddeelliivveerryysslloottss))

Idem, for delivery via the named message transport. ddeeffaauullttddeelliivveerryysslloottddiissccoouunntt ((5500))

The default value for transport-specific deliveryslotdiscount

settings.

transportddeelliivveerryysslloottddiissccoouunntt (($$ddeeffaauullttddeelliivveerryysslloottddiissccoouunntt))

Idem, for delivery via the named message transport. ddeeffaauullttddeelliivveerryysslloottllooaann ((33))

The default value for transport-specific deliveryslotloan

settings.

transportddeelliivveerryysslloottllooaann (($$ddeeffaauullttddeelliivveerryysslloottllooaann))

Idem, for delivery via the named message transport. OOTTHHEERR RREESSOOUURRCCEE AANNDD RRAATTEE CCOONNTTRROOLLSS mmiinniimmaallbbaacckkooffffttiimmee ((11000000ss)) The minimal time between attempts to deliver a deferred message. mmaaxxiimmaallbbaacckkooffffttiimmee ((44000000ss)) The maximal time between attempts to deliver a deferred message. mmaaxxiimmaallqquueeuueelliiffeettiimmee ((55dd)) The maximal time a message is queued before it is sent back as undeliverable. qquueeuueerruunnddeellaayy ((11000000ss)) The time between deferred queue scans by the queue manager. ttrraannssppoorrttrreettrryyttiimmee ((6600ss))

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: bboouunncceeqquueeuueelliiffeettiimmee ((55dd))

The maximal time a bounce message is queued before it is consid-

ered undeliverable. MMIISSCCEELLLLAANNEEOOUUSS CCOONNTTRROOLLSS

ccoonnffiiggddiirreeccttoorryy ((sseeee ''ppoossttccoonnff -dd'' oouuttppuutt))

The default location of the Postfix main.cf and master.cf con-

figuration files. ddaaeemmoonnttiimmeeoouutt ((1188000000ss)) How much time a Postfix daemon process may take to handle a

request before it is terminated by a built-in watchdog timer.

ddeeffeerrttrraannssppoorrttss ((eemmppttyy)) The names of message delivery transports that should not be

delivered to unless someone issues "sseennddmmaaiill -qq" or equivalent.

hheellppffuullwwaarrnniinnggss ((yyeess))

Log warnings about problematic configuration settings, and pro-

vide helpful suggestions. iippccttiimmeeoouutt ((33660000ss)) The time limit for sending or receiving information over an internal communication channel.

pprroocceessssiidd ((rreeaadd-oonnllyy))

The process ID of a Postfix command or daemon process.

pprroocceessssnnaammee ((rreeaadd-oonnllyy))

The process name of a Postfix command or daemon process.

qquueeuueeddiirreeccttoorryy ((sseeee ''ppoossttccoonnff -dd'' oouuttppuutt))

The location of the Postfix top-level queue directory.

ssyyssllooggffaacciilliittyy ((mmaaiill)) The syslog facility of Postfix logging. ssyyssllooggnnaammee ((ppoossttffiixx)) 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