1PIPE(8) System Manager's Manual PIPE(8)
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6 pipe - Postfix delivery to external command
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9 pipe [generic Postfix daemon options] command_attributes...
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12 The pipe(8) daemon processes requests from the Postfix queue manager to
13 deliver messages to external commands. This program expects to be run
14 from the master(8) process manager.
15 Message attributes such as sender address, recipient address and
17 next-hop host name can be specified as command-line macros that are
18 expanded before the external command is executed.
19 The pipe(8) daemon updates queue files and marks recipients as fin‐
21 ished, or it informs the queue manager that delivery should be tried
22 again at a later time. Delivery status reports are sent to the
23 bounce(8), defer(8) or trace(8) daemon as appropriate.
24
26 Some destinations cannot handle more than one recipient per delivery
27 request. Examples are pagers or fax machines. In addition,
28 multi-recipient delivery is undesirable when prepending a Delivered-to:
29 or X-Original-To: message header.
30 To prevent Postfix from sending multiple recipients per delivery
32 request, specify
33 transport_destination_recipient_limit = 1
35 in the Postfix main.cf file, where transport is the name in the first
37 column of the Postfix master.cf entry for the pipe-based delivery
38 transport.
39
41 The external command attributes are given in the master.cf file at the
42 end of a service definition. The syntax is as follows:
43 chroot=pathname (optional)
45 Change the process root directory and working directory to the
46 named directory. This happens before switching to the privileges
47 specified with the user attribute, and before executing the
48 optional directory=pathname directive. Delivery is deferred in
49 case of failure.
50 This feature is available as of Postfix 2.3.
52 directory=pathname (optional)
54 Change to the named directory before executing the external com‐
55 mand. The directory must be accessible for the user specified
56 with the user attribute (see below). The default working direc‐
57 tory is $queue_directory. Delivery is deferred in case of fail‐
58 ure.
59 This feature is available as of Postfix 2.2.
61 eol=string (optional, default: \n)
63 The output record delimiter. Typically one would use either \r\n
64 or \n. The usual C-style backslash escape sequences are recog‐
65 nized: \a \b \f \n \r \t \v \ddd (up to three octal digits) and
66 \\.
67 flags=BDFORXhqu.> (optional)
69 Optional message processing flags. By default, a message is
70 copied unchanged.
71 B Append a blank line at the end of each message. This is
73 required by some mail user agents that recognize "From "
74 lines only when preceded by a blank line.
75 D Prepend a "Delivered-To: recipient" message header with
77 the envelope recipient address. Note: for this to work,
78 the transport_destination_recipient_limit must be 1 (see
79 SINGLE-RECIPIENT DELIVERY above for details).
80 The D flag also enforces loop detection (Postfix 2.5 and
82 later): if a message already contains a Delivered-To:
83 header with the same recipient address, then the message
84 is returned as undeliverable. The address comparison is
85 case insensitive.
86 This feature is available as of Postfix 2.0.
88 F Prepend a "From sender time_stamp" envelope header to the
90 message content. This is expected by, for example, UUCP
91 software.
92 O Prepend an "X-Original-To: recipient" message header with
94 the recipient address as given to Postfix. Note: for this
95 to work, the transport_destination_recipient_limit must
96 be 1 (see SINGLE-RECIPIENT DELIVERY above for details).
97 This feature is available as of Postfix 2.0.
99 R Prepend a Return-Path: message header with the envelope
101 sender address.
102 X Indicate that the external command performs final deliv‐
104 ery. This flag affects the status reported in "success"
105 DSN (delivery status notification) messages, and changes
106 it from "relayed" into "delivered".
107 This feature is available as of Postfix 2.5.
109 h Fold the command-line $original_recipient and $recipient
111 address domain part (text to the right of the right-most
112 @ character) to lower case; fold the entire command-line
113 $domain and $nexthop host or domain information to lower
114 case. This is recommended for delivery via UUCP.
115 q Quote white space and other special characters in the
117 command-line $sender, $original_recipient and $recipient
118 address localparts (text to the left of the right-most @
119 character), according to an 8-bit transparent version of
120 RFC 822. This is recommended for delivery via UUCP or
121 BSMTP.
122 The result is compatible with the address parsing of com‐
124 mand-line recipients by the Postfix sendmail(1) mail sub‐
125 mission command.
126 The q flag affects only entire addresses, not the partial
128 address information from the $user, $extension or $mail‐
129 box command-line macros.
130 u Fold the command-line $original_recipient and $recipient
132 address localpart (text to the left of the right-most @
133 character) to lower case. This is recommended for deliv‐
134 ery via UUCP.
135 . Prepend "." to lines starting with ".". This is needed
137 by, for example, BSMTP software.
138 > Prepend ">" to lines starting with "From ". This is
140 expected by, for example, UUCP software.
141 null_sender=replacement (default: MAILER-DAEMON)
143 Replace the null sender address (typically used for delivery
144 status notifications) with the specified text when expanding the
145 $sender command-line macro, and when generating a From_ or
146 Return-Path: message header.
147 If the null sender replacement text is a non-empty string then
149 it is affected by the q flag for address quoting in command-line
150 arguments.
151 The null sender replacement text may be empty; this form is rec‐
153 ommended for content filters that feed mail back into Postfix.
154 The empty sender address is not affected by the q flag for
155 address quoting in command-line arguments.
156 Caution: a null sender address is easily mis-parsed by naive
158 software. For example, when the pipe(8) daemon executes a com‐
159 mand such as:
160 Wrong: command -f$sender -- $recipient
162 the command will mis-parse the -f option value when the sender
164 address is a null string. For correct parsing, specify $sender
165 as an argument by itself:
166 Right: command -f $sender -- $recipient
168 This feature is available as of Postfix 2.3.
170 size=size_limit (optional)
172 Don't deliver messages that exceed this size limit (in bytes);
173 return them to the sender instead.
174 user=username (required)
176 user=username:groupname
178 Execute the external command with the user ID and group ID of
179 the specified username. The software refuses to execute com‐
180 mands with root privileges, or with the privileges of the mail
181 system owner. If groupname is specified, the corresponding group
182 ID is used instead of the group ID of username.
183 argv=command... (required)
185 The command to be executed. This must be specified as the last
186 command attribute. The command is executed directly, i.e. with‐
187 out interpretation of shell meta characters by a shell command
188 interpreter.
189 Specify "{" and "}" around command arguments that contain white‐
191 space (Postfix 3.0 and later). Whitespace after the opening "{"
192 and before the closing "}" is ignored.
193 In the command argument vector, the following macros are recog‐
195 nized and replaced with corresponding information from the Post‐
196 fix queue manager delivery request.
197 In addition to the form ${name}, the forms $name and the depre‐
199 cated form $(name) are also recognized. Specify $$ where a sin‐
200 gle $ is wanted.
201 ${client_address}
203 This macro expands to the remote client network address.
204 This feature is available as of Postfix 2.2.
206 ${client_helo}
208 This macro expands to the remote client HELO command
209 parameter.
210 This feature is available as of Postfix 2.2.
212 ${client_hostname}
214 This macro expands to the remote client hostname.
215 This feature is available as of Postfix 2.2.
217 ${client_port}
219 This macro expands to the remote client TCP port number.
220 This feature is available as of Postfix 2.5.
222 ${client_protocol}
224 This macro expands to the remote client protocol.
225 This feature is available as of Postfix 2.2.
227 ${domain}
229 This macro expands to the domain portion of the recipient
230 address. For example, with an address user+foo@domain
231 the domain is domain.
232 This information is modified by the h flag for case fold‐
234 ing.
235 This feature is available as of Postfix 2.5.
237 ${extension}
239 This macro expands to the extension part of a recipient
240 address. For example, with an address user+foo@domain
241 the extension is foo.
242 A command-line argument that contains ${extension}
244 expands into as many command-line arguments as there are
245 recipients.
246 This information is modified by the u flag for case fold‐
248 ing.
249 ${mailbox}
251 This macro expands to the complete local part of a recip‐
252 ient address. For example, with an address
253 user+foo@domain the mailbox is user+foo.
254 A command-line argument that contains ${mailbox} expands
256 to as many command-line arguments as there are recipi‐
257 ents.
258 This information is modified by the u flag for case fold‐
260 ing.
261 ${nexthop}
263 This macro expands to the next-hop hostname.
264 This information is modified by the h flag for case fold‐
266 ing.
267 ${original_recipient}
269 This macro expands to the complete recipient address
270 before any address rewriting or aliasing.
271 A command-line argument that contains ${original_recipi‐
273 ent} expands to as many command-line arguments as there
274 are recipients.
275 This information is modified by the hqu flags for quoting
277 and case folding.
278 This feature is available as of Postfix 2.5.
280 ${queue_id}
282 This macro expands to the queue id.
283 This feature is available as of Postfix 2.11.
285 ${recipient}
287 This macro expands to the complete recipient address.
288 A command-line argument that contains ${recipient}
290 expands to as many command-line arguments as there are
291 recipients.
292 This information is modified by the hqu flags for quoting
294 and case folding.
295 ${sasl_method}
297 This macro expands to the name of the SASL authentication
298 mechanism in the AUTH command when the Postfix SMTP
299 server received the message.
300 This feature is available as of Postfix 2.2.
302 ${sasl_sender}
304 This macro expands to the SASL sender name (i.e. the
305 original submitter as per RFC 4954) in the MAIL FROM com‐
306 mand when the Postfix SMTP server received the message.
307 This feature is available as of Postfix 2.2.
309 ${sasl_username}
311 This macro expands to the SASL user name in the AUTH com‐
312 mand when the Postfix SMTP server received the message.
313 This feature is available as of Postfix 2.2.
315 ${sender}
317 This macro expands to the envelope sender address. By
318 default, the null sender address expands to MAILER-DAE‐
319 MON; this can be changed with the null_sender attribute,
320 as described above.
321 This information is modified by the q flag for quoting.
323 ${size}
325 This macro expands to Postfix's idea of the message size,
326 which is an approximation of the size of the message as
327 delivered.
328 ${user}
330 This macro expands to the username part of a recipient
331 address. For example, with an address user+foo@domain
332 the username part is user.
333 A command-line argument that contains ${user} expands
335 into as many command-line arguments as there are recipi‐
336 ents.
337 This information is modified by the u flag for case fold‐
339 ing.
340
342 RFC 3463 (Enhanced status codes)
343
345 Command exit status codes are expected to follow the conventions
346 defined in <sysexits.h>. Exit status 0 means normal successful comple‐
347 tion.
348 In the case of a non-zero exit status, a limited amount of command out‐
350 put is logged, and reported in a delivery status notification. When
351 the output begins with a 4.X.X or 5.X.X enhanced status code, the sta‐
352 tus code takes precedence over the non-zero exit status (Postfix ver‐
353 sion 2.3 and later).
354 After successful delivery (zero exit status) a limited amount of com‐
356 mand output is logged, and reported in "success" delivery status noti‐
357 fications (Postfix 3.0 and later). This command output is not examined
358 for the presence of an enhanced status code.
359 Problems and transactions are logged to syslogd(8) or postlogd(8).
361 Corrupted message files are marked so that the queue manager can move
362 them to the corrupt queue for further inspection.
363
365 This program needs a dual personality 1) to access the private Postfix
366 queue and IPC mechanisms, and 2) to execute external commands as the
367 specified user. It is therefore security sensitive.
368
370 Changes to main.cf are picked up automatically as pipe(8) processes run
371 for only a limited amount of time. Use the command "postfix reload" to
372 speed up a change.
373 The text below provides only a parameter summary. See postconf(5) for
375 more details including examples.
376
378 In the text below, transport is the first field in a master.cf entry.
379 transport_time_limit ($command_time_limit)
381 A transport-specific override for the command_time_limit parame‐
382 ter value, where transport is the master.cf name of the message
383 delivery transport.
384 Implemented in the qmgr(8) daemon:
386 transport_destination_concurrency_limit ($default_destination_concur‐
388 rency_limit)
389 A transport-specific override for the default_destination_con‐
390 currency_limit parameter value, where transport is the master.cf
391 name of the message delivery transport.
392 transport_destination_recipient_limit ($default_destination_recipi‐
394 ent_limit)
395 A transport-specific override for the default_destination_recip‐
396 ient_limit parameter value, where transport is the master.cf
397 name of the message delivery transport.
398
400 config_directory (see 'postconf -d' output)
401 The default location of the Postfix main.cf and master.cf con‐
402 figuration files.
403 daemon_timeout (18000s)
405 How much time a Postfix daemon process may take to handle a
406 request before it is terminated by a built-in watchdog timer.
407 delay_logging_resolution_limit (2)
409 The maximal number of digits after the decimal point when log‐
410 ging sub-second delay values.
411 export_environment (see 'postconf -d' output)
413 The list of environment variables that a Postfix process will
414 export to non-Postfix processes.
415 ipc_timeout (3600s)
417 The time limit for sending or receiving information over an
418 internal communication channel.
419 mail_owner (postfix)
421 The UNIX system account that owns the Postfix queue and most
422 Postfix daemon processes.
423 max_idle (100s)
425 The maximum amount of time that an idle Postfix daemon process
426 waits for an incoming connection before terminating voluntarily.
427 max_use (100)
429 The maximal number of incoming connections that a Postfix daemon
430 process will service before terminating voluntarily.
431 process_id (read-only)
433 The process ID of a Postfix command or daemon process.
434 process_name (read-only)
436 The process name of a Postfix command or daemon process.
437 queue_directory (see 'postconf -d' output)
439 The location of the Postfix top-level queue directory.
440 recipient_delimiter (empty)
442 The set of characters that can separate a user name from its
443 extension (example: user+foo), or a .forward file name from its
444 extension (example: .forward+foo).
445 syslog_facility (mail)
447 The syslog facility of Postfix logging.
448 syslog_name (see 'postconf -d' output)
450 A prefix that is prepended to the process name in syslog
451 records, so that, for example, "smtpd" becomes "prefix/smtpd".
452 Available in Postfix version 3.0 and later:
454 pipe_delivery_status_filter ($default_delivery_status_filter)
456 Optional filter for the pipe(8) delivery agent to change the
457 delivery status code or explanatory text of successful or unsuc‐
458 cessful deliveries.
459 Available in Postfix version 3.3 and later:
461 enable_original_recipient (yes)
463 Enable support for the original recipient address after an
464 address is rewritten to a different address (for example with
465 aliasing or with canonical mapping).
466 service_name (read-only)
468 The master.cf service name of a Postfix daemon process.
469 Available in Postfix 3.5 and later:
471 info_log_address_format (external)
473 The email address form that will be used in non-debug logging
474 (info, warning, etc.).
475
477 qmgr(8), queue manager
478 bounce(8), delivery status reports
479 postconf(5), configuration parameters
480 master(5), generic daemon options
481 master(8), process manager
482 postlogd(8), Postfix logging
483 syslogd(8), system logging
484
486 The Secure Mailer license must be distributed with this software.
487
489 Wietse Venema
490 IBM T.J. Watson Research
491 P.O. Box 704
492 Yorktown Heights, NY 10598, USA
493 Wietse Venema
495 Google, Inc.
496 111 8th Avenue
497 New York, NY 10011, USA
498 PIPE(8)