1OQMGR(8)                    System Manager's Manual                   OQMGR(8)
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NAME

6       oqmgr - old Postfix queue manager
7

SYNOPSIS

9       oqmgr [generic Postfix daemon options]
10

DESCRIPTION

12       The  oqmgr(8)  daemon  awaits the arrival of incoming mail and arranges
13       for its delivery via Postfix delivery processes.  The actual mail rout‐
14       ing  strategy is delegated to the trivial-rewrite(8) daemon.  This pro‐
15       gram expects to be run from the master(8) process manager.
16
17       Mail addressed to the local double-bounce address is  logged  and  dis‐
18       carded.   This  stops  potential  loops  caused by undeliverable bounce
19       notifications.
20

MAIL QUEUES

22       The oqmgr(8) daemon maintains the following queues:
23
24       incoming
25              Inbound mail from the network, or mail picked up  by  the  local
26              pickup(8) agent from the maildrop directory.
27
28       active Messages  that the queue manager has opened for delivery. Only a
29              limited number of messages is allowed to enter the active  queue
30              (leaky bucket strategy, for a fixed delivery rate).
31
32       deferred
33              Mail  that  could  not  be delivered upon the first attempt. The
34              queue manager implements exponential  backoff  by  doubling  the
35              time between delivery attempts.
36
37       corrupt
38              Unreadable or damaged queue files are moved here for inspection.
39
40       hold   Messages  that  are  kept  "on hold" are kept here until someone
41              sets them free.
42

DELIVERY STATUS REPORTS

44       The oqmgr(8) daemon keeps an eye on per-message delivery status reports
45       in the following directories. Each status report file has the same name
46       as the corresponding message file:
47
48       bounce Per-recipient status information  about  why  mail  is  bounced.
49              These files are maintained by the bounce(8) daemon.
50
51       defer  Per-recipient  status  information  about  why  mail is delayed.
52              These files are maintained by the defer(8) daemon.
53
54       trace  Per-recipient status information as requested with  the  Postfix
55              "sendmail  -v" or "sendmail -bv" command.  These files are main‐
56              tained by the trace(8) daemon.
57
58       The oqmgr(8) daemon is responsible for asking the  bounce(8),  defer(8)
59       or trace(8) daemons to send delivery reports.
60

STRATEGIES

62       The queue manager implements a variety of strategies for either opening
63       queue files (input) or for message delivery (output).
64
65       leaky bucket
66              This strategy limits the number of messages in the active  queue
67              and  prevents the queue manager from running out of memory under
68              heavy load.
69
70       fairness
71              When the active queue has room, the queue manager takes one mes‐
72              sage  from  the  incoming queue and one from the deferred queue.
73              This prevents a large mail backlog from blocking the delivery of
74              new mail.
75
76       slow start
77              This  strategy  eliminates  "thundering herd" problems by slowly
78              adjusting the number of parallel deliveries to the same destina‐
79              tion.
80
81       round robin
82              The  queue  manager  sorts  delivery  requests  by  destination.
83              Round-robin selection prevents one destination  from  dominating
84              deliveries to other destinations.
85
86       exponential backoff
87              Mail  that  cannot  be  delivered  upon  the  first  attempt  is
88              deferred.  The time interval between delivery attempts  is  dou‐
89              bled after each attempt.
90
91       destination status cache
92              The  queue manager avoids unnecessary delivery attempts by main‐
93              taining a short-term, in-memory  list  of  unreachable  destina‐
94              tions.
95

TRIGGERS

97       On  an  idle system, the queue manager waits for the arrival of trigger
98       events, or it waits for a timer to go off. A trigger is a one-byte mes‐
99       sage.   Depending  on  the message received, the queue manager performs
100       one of the following actions (the message is followed by  the  symbolic
101       constant used internally by the software):
102
103       D (QMGR_REQ_SCAN_DEFERRED)
104              Start  a  deferred  queue  scan.   If  a  deferred queue scan is
105              already in progress, that scan will be restarted as soon  as  it
106              finishes.
107
108       I (QMGR_REQ_SCAN_INCOMING)
109              Start  an  incoming  queue  scan.  If  an incoming queue scan is
110              already in progress, that scan will be restarted as soon  as  it
111              finishes.
112
113       A (QMGR_REQ_SCAN_ALL)
114              Ignore  deferred queue file time stamps. The request affects the
115              next deferred queue scan.
116
117       F (QMGR_REQ_FLUSH_DEAD)
118              Purge all information about dead transports and destinations.
119
120       W (TRIGGER_REQ_WAKEUP)
121              Wakeup call, This is used by the master  server  to  instantiate
122              servers  that should not go away forever. The action is to start
123              an incoming queue scan.
124
125       The oqmgr(8) daemon reads an entire buffer worth of triggers.  Multiple
126       identical trigger requests are collapsed into one, and trigger requests
127       are sorted so that A and F precede D and I. Thus, in order to  force  a
128       deferred  queue  run,  one  would request A F D; in order to notify the
129       queue manager of the arrival of new mail one would request I.
130

STANDARDS

132       RFC 3463 (Enhanced status codes)
133       RFC 3464 (Delivery status notifications)
134

SECURITY

136       The oqmgr(8) daemon is not security sensitive. It reads  single-charac‐
137       ter messages from untrusted local users, and thus may be susceptible to
138       denial of service attacks. The oqmgr(8) daemon does  not  talk  to  the
139       outside  world,  and it can be run at fixed low privilege in a chrooted
140       environment.
141

DIAGNOSTICS

143       Problems and transactions are logged to  the  syslog(8)  daemon.   Cor‐
144       rupted message files are saved to the corrupt queue for further inspec‐
145       tion.
146
147       Depending on the setting of the notify_classes parameter, the  postmas‐
148       ter is notified of bounces and of other trouble.
149

BUGS

151       A single queue manager process has to compete for disk access with mul‐
152       tiple front-end processes such as cleanup(8). A sudden burst of inbound
153       mail can negatively impact outbound delivery rates.
154

CONFIGURATION PARAMETERS

156       Changes  to  main.cf  are not picked up automatically, as oqmgr(8) is a
157       persistent process. Use the command "postfix reload" after a configura‐
158       tion change.
159
160       The  text  below provides only a parameter summary. See postconf(5) for
161       more details including examples.
162
163       In the text below, transport is the first field in a master.cf entry.
164

COMPATIBILITY CONTROLS

166       Available before Postfix version 2.5:
167
168       allow_min_user (no)
169              Allow a sender or recipient address to have  `-'  as  the  first
170              character.
171
172       Available with Postfix version 2.7 and later:
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174       default_filter_nexthop (empty)
175              When  a  content_filter  or FILTER request specifies no explicit
176              next-hop destination, use $default_filter_nexthop instead;  when
177              that value is empty, use the domain in the recipient address.
178

ACTIVE QUEUE CONTROLS

180       qmgr_clog_warn_time (300s)
181              The  minimal  delay between warnings that a specific destination
182              is clogging up the Postfix active queue.
183
184       qmgr_message_active_limit (20000)
185              The maximal number of messages in the active queue.
186
187       qmgr_message_recipient_limit (20000)
188              The maximal number of recipients held in memory by  the  Postfix
189              queue manager, and the maximal size of the short-term, in-memory
190              "dead" destination status cache.
191

DELIVERY CONCURRENCY CONTROLS

193       qmgr_fudge_factor (100)
194              Obsolete feature: the percentage of delivery  resources  that  a
195              busy  mail  system  will  use up for delivery of a large mailing
196              list message.
197
198       initial_destination_concurrency (5)
199              The  initial  per-destination  concurrency  level  for  parallel
200              delivery to the same destination.
201
202       default_destination_concurrency_limit (20)
203              The  default  maximal  number of parallel deliveries to the same
204              destination.
205
206       transport_destination_concurrency_limit   ($default_destination_concur‐
207       rency_limit)
208              Idem, for delivery via the named message transport.
209
210       Available in Postfix version 2.5 and later:
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212       transport_initial_destination_concurrency ($initial_destination_concur‐
213       rency)
214              Initial concurrency for delivery via the  named  message  trans‐
215              port.
216
217       default_destination_concurrency_failed_cohort_limit (1)
218              How  many  pseudo-cohorts  must  suffer  connection or handshake
219              failure before a specific destination is considered  unavailable
220              (and further delivery is suspended).
221
222       transport_destination_concurrency_failed_cohort_limit  ($default_desti‐
223       nation_concurrency_failed_cohort_limit)
224              Idem, for delivery via the named message transport.
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226       default_destination_concurrency_negative_feedback (1)
227              The per-destination  amount  of  delivery  concurrency  negative
228              feedback,  after a delivery completes with a connection or hand‐
229              shake failure.
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231       transport_destination_concurrency_negative_feedback  ($default_destina‐
232       tion_concurrency_negative_feedback)
233              Idem, for delivery via the named message transport.
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235       default_destination_concurrency_positive_feedback (1)
236              The  per-destination  amount  of  delivery  concurrency positive
237              feedback, after a delivery completes without connection or hand‐
238              shake failure.
239
240       transport_destination_concurrency_positive_feedback  ($default_destina‐
241       tion_concurrency_positive_feedback)
242              Idem, for delivery via the named message transport.
243
244       destination_concurrency_feedback_debug (no)
245              Make the queue manager's feedback algorithm verbose for  perfor‐
246              mance analysis purposes.
247

RECIPIENT SCHEDULING CONTROLS

249       default_destination_recipient_limit (50)
250              The default maximal number of recipients per message delivery.
251
252       transport_destination_recipient_limit
253              Idem, for delivery via the named message transport.
254

OTHER RESOURCE AND RATE CONTROLS

256       minimal_backoff_time (300s)
257              The minimal time between attempts to deliver a deferred message;
258              prior to Postfix 2.4 the default value was 1000s.
259
260       maximal_backoff_time (4000s)
261              The maximal time between attempts to deliver a deferred message.
262
263       maximal_queue_lifetime (5d)
264              The maximal time a message is queued before it is sent  back  as
265              undeliverable.
266
267       queue_run_delay (300s)
268              The  time  between  deferred  queue  scans by the queue manager;
269              prior to Postfix 2.4 the default value was 1000s.
270
271       transport_retry_time (60s)
272              The time between attempts by the Postfix queue manager  to  con‐
273              tact a malfunctioning message delivery transport.
274
275       Available in Postfix version 2.1 and later:
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277       bounce_queue_lifetime (5d)
278              The maximal time a bounce message is queued before it is consid‐
279              ered undeliverable.
280
281       Available in Postfix version 2.5 and later:
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283       default_destination_rate_delay (0s)
284              The default amount of delay that is inserted between  individual
285              deliveries  to  the  same  destination;  the  resulting behavior
286              depends on the value of the corresponding per-destination recip‐
287              ient limit.
288
289       transport_destination_rate_delay $default_destination_rate_delay
290              Idem, for delivery via the named message transport.
291

SAFETY CONTROLS

293       qmgr_daemon_timeout (1000s)
294              How much time a Postfix queue manager process may take to handle
295              a request before it is terminated by a built-in watchdog timer.
296
297       qmgr_ipc_timeout (60s)
298              The time limit for the queue manager to send or receive informa‐
299              tion over an internal communication channel.
300

MISCELLANEOUS CONTROLS

302       config_directory (see 'postconf -d' output)
303              The  default  location of the Postfix main.cf and master.cf con‐
304              figuration files.
305
306       defer_transports (empty)
307              The names of message delivery transports that should not deliver
308              mail unless someone issues "sendmail -q" or equivalent.
309
310       delay_logging_resolution_limit (2)
311              The  maximal  number of digits after the decimal point when log‐
312              ging sub-second delay values.
313
314       helpful_warnings (yes)
315              Log warnings about problematic configuration settings, and  pro‐
316              vide helpful suggestions.
317
318       process_id (read-only)
319              The process ID of a Postfix command or daemon process.
320
321       process_name (read-only)
322              The process name of a Postfix command or daemon process.
323
324       queue_directory (see 'postconf -d' output)
325              The location of the Postfix top-level queue directory.
326
327       syslog_facility (mail)
328              The syslog facility of Postfix logging.
329
330       syslog_name (see 'postconf -d' output)
331              The  mail  system  name that is prepended to the process name in
332              syslog records, so that "smtpd"  becomes,  for  example,  "post‐
333              fix/smtpd".
334

FILES

336       /var/spool/postfix/incoming, incoming queue
337       /var/spool/postfix/active, active queue
338       /var/spool/postfix/deferred, deferred queue
339       /var/spool/postfix/bounce, non-delivery status
340       /var/spool/postfix/defer, non-delivery status
341       /var/spool/postfix/trace, delivery status
342

SEE ALSO

344       trivial-rewrite(8), address routing
345       bounce(8), delivery status reports
346       postconf(5), configuration parameters
347       master(5), generic daemon options
348       master(8), process manager
349       syslogd(8), system logging
350

README FILES

352       Use  "postconf readme_directory" or "postconf html_directory" to locate
353       this information.
354       QSHAPE_README, Postfix queue analysis
355

LICENSE

357       The Secure Mailer license must be distributed with this software.
358

AUTHOR(S)

360       Wietse Venema
361       IBM T.J. Watson Research
362       P.O. Box 704
363       Yorktown Heights, NY 10598, USA
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367                                                                      OQMGR(8)
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