--- name: "oqmgr" section: "8" platform: "linux" package: "postfix" version: "3.11.7-1" release: "Arch Linux 2026-11-01" platforms: ["linux", "macos"] url: "https://new.carta.tech/oqmgr" --- # oqmgr(8) old Postfix queue manager ## NAME oqmgr - old Postfix queue manager ## SYNOPSIS ``` oqmgr [generic Postfix daemon options] ``` ## DESCRIPTION The [**oqmgr**(8)](/oqmgr/8.md) 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)](/trivial-rewrite/8.md) daemon. This program expects to be run from the [**master**(8)](/master/8.md) 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)](/oqmgr/8.md) daemon maintains the following queues: - **incoming** Inbound mail from the network, or mail picked up by the local [**pickup**(8)](/pickup/8.md) 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). - **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)](/oqmgr/8.md) 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)](/bounce/8.md) daemon. - **defer** Per-recipient status information about why mail is delayed. These files are maintained by the [**defer**(8)](/defer/8.md) 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)](/trace/8.md) daemon. The [**oqmgr**(8)](/oqmgr/8.md) daemon is responsible for asking the [**bounce**(8)](/bounce/8.md), [**defer**(8)](/defer/8.md) or [**trace**(8)](/trace/8.md) 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 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 forever. The action is to start an incoming queue scan. The [**oqmgr**(8)](/oqmgr/8.md) 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)](/oqmgr/8.md) 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)](/oqmgr/8.md) 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 [**syslogd**(8)](/syslogd/8.md) or [**postlogd**(8)](/postlogd/8.md) 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)](/cleanup/8.md). 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)](/oqmgr/8.md) is a persistent process. Use the command "**postfix reload**" after a configuration change. The text below provides only a parameter summary. See [**postconf**(5)](/postconf/5.md) for more details including examples. 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 $default\_filter\_nexthop instead; when that value is empty, use the domain in the recipient address. ## ACTIVE QUEUE CONTROLS ``` ``` - **qmgr\_clog\_warn\_time (300s)** The minimal delay between warnings that a specific destination is clogging up the Postfix active queue. - **qmgr\_message\_active\_limit (20000)** The maximal number of messages in the active queue. - **qmgr\_message\_recipient\_limit (20000)** The maximal number of recipients held in memory by the Postfix queue manager, and the maximal size of the short-term, in-memory "dead" destination status cache. ## DELIVERY CONCURRENCY CONTROLS ``` ``` - **qmgr\_fudge\_factor (100)** Obsolete feature: the percentage of delivery resources that a busy mail system will use up for delivery of a large mailing list message. - **initial\_destination\_concurrency (5)** The initial per-destination concurrency level for parallel delivery to the same destination. - **default\_destination\_concurrency\_limit (20)** The default maximal number of parallel deliveries to the same destination. - **transport\_destination\_concurrency\_limit ($default\_destination\_concurrency\_limit)** A transport-specific override for the default\_destination\_concurrency\_limit parameter value, where *transport* is the master.cf name of the message delivery transport. Available in Postfix version 2.5 and later: - **transport\_initial\_destination\_concurrency ($initial\_destination\_concurrency)** A transport-specific override for the initial\_destination\_concurrency parameter value, where *transport* is the master.cf name of the message delivery transport. - **default\_destination\_concurrency\_failed\_cohort\_limit (1)** How many pseudo-cohorts must suffer connection or handshake failure before a specific destination is considered unavailable (and further delivery is suspended). - **transport\_destination\_concurrency\_failed\_cohort\_limit ($default\_destination\_concurrency\_failed\_cohort\_limit)** A transport-specific override for the default\_destination\_concurrency\_failed\_cohort\_limit parameter value, where *transport* is the master.cf name of the message delivery transport. - **default\_destination\_concurrency\_negative\_feedback (1)** The per-destination amount of delivery concurrency negative feedback, after a delivery completes with a connection or handshake failure. - **transport\_destination\_concurrency\_negative\_feedback ($default\_destination\_concurrency\_negative\_feedback)** A transport-specific override for the default\_destination\_concurrency\_negative\_feedback parameter value, where *transport* is the master.cf name of the message delivery transport. - **default\_destination\_concurrency\_positive\_feedback (1)** The per-destination amount of delivery concurrency positive feedback, after a delivery completes without connection or handshake failure. - **transport\_destination\_concurrency\_positive\_feedback ($default\_destination\_concurrency\_positive\_feedback)** A transport-specific override for the default\_destination\_concurrency\_positive\_feedback parameter value, where *transport* is the master.cf name of the message delivery 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 ($default\_destination\_recipient\_limit)** A transport-specific override for the default\_destination\_recipient\_limit parameter value, where *transport* is the master.cf name of the message delivery transport. ## OTHER RESOURCE AND RATE CONTROLS ``` ``` - **minimal\_backoff\_time (300s)** The minimal time between attempts to deliver a deferred message; prior to Postfix 2.4 the default value was 1000s. - **maximal\_backoff\_time (4000s)** The maximal time between attempts to deliver a deferred message. - **maximal\_queue\_lifetime (5d)** Consider a message as undeliverable, when delivery fails with a temporary error, and the time in the queue has reached the maximal\_queue\_lifetime limit. - **queue\_run\_delay (300s)** The time between deferred queue scans by the queue manager; prior to Postfix 2.4 the default value was 1000s. - **transport\_retry\_time (60s)** The time between attempts by the Postfix queue manager to contact a malfunctioning message delivery transport. Available in Postfix version 2.1 and later: - **bounce\_queue\_lifetime (5d)** Consider a bounce message as undeliverable, when delivery fails with a temporary error, and the time in the queue has reached the bounce\_queue\_lifetime limit. Available in Postfix version 2.5 and later: - **default\_destination\_rate\_delay (0s)** The default amount of delay that is inserted between individual message deliveries to the same destination and over the same message delivery transport. - **transport\_destination\_rate\_delay ($default\_destination\_rate\_delay)** A transport-specific override for the default\_destination\_rate\_delay parameter value, where *transport* is the master.cf name of the message delivery transport. Available in Postfix version 3.1 and later: - **default\_transport\_rate\_delay (0s)** The default amount of delay that is inserted between individual message deliveries over the same message delivery transport, regardless of destination. - **transport\_transport\_rate\_delay ($default\_transport\_rate\_delay)** A transport-specific override for the default\_transport\_rate\_delay parameter value, where the initial *transport* in the parameter name is the master.cf name of the message delivery transport. ## SAFETY CONTROLS ``` ``` - **qmgr\_daemon\_timeout (1000s)** How much time a Postfix queue manager process may take to handle a request before it is terminated 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 communication channel. Available in Postfix version 3.1 and later: - **address\_verify\_pending\_request\_limit (see 'postconf -d' output)** A safety limit that prevents address verification requests from overwhelming the Postfix queue. ## 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 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)** A prefix that is prepended to the process name in syslog records, so that, for example, "smtpd" becomes "prefix/smtpd". Available in Postfix version 3.0 and later: - **confirm\_delay\_cleared (no)** After sending a "your message is delayed" notification, inform the sender when the delay clears up. Available in Postfix 3.3 and later: - **service\_name (read-only)** The master.cf service name of a Postfix daemon process. Available in Postfix 3.5 and later: - **info\_log\_address\_format (external)** The email address form that will be used in non-debug logging (info, warning, etc.). ## 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 postlogd(8), Postfix logging 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 Wietse Venema Google, Inc. 111 8th Avenue New York, NY 10011, USA ```