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 next-
17 hop host name can be specified as command-line macros that are expanded
18 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 external commands cannot handle more than one recipient per deliv‐
27 ery request. Examples of such transports are pagers or fax machines.
28 To prevent Postfix from sending multiple recipients per delivery
30 request, specify
31 transport_destination_recipient_limit = 1
33 in the Postfix main.cf file, where transport is the name in the first
35 column of the Postfix master.cf entry for the pipe-based delivery
36 transport.
37
39 The external command attributes are given in the master.cf file at the
40 end of a service definition. The syntax is as follows:
41 chroot=pathname (optional)
43 Change the process root directory and working directory to the
44 named directory. This happens before switching to the privileges
45 specified with the user attribute, and before executing the
46 optional directory=pathname directive. Delivery is deferred in
47 case of failure.
48 This feature is available as of Postfix 2.3.
50 directory=pathname (optional)
52 Change to the named directory before executing the external com‐
53 mand. The directory must be accessible for the user specified
54 with the user attribute (see below). The default working direc‐
55 tory is $queue_directory. Delivery is deferred in case of fail‐
56 ure.
57 This feature is available as of Postfix 2.2.
59 eol=string (optional, default: \n)
61 The output record delimiter. Typically one would use either \r\n
62 or \n. The usual C-style backslash escape sequences are recog‐
63 nized: \a \b \f \n \r \t \v \ddd (up to three octal digits) and
64 \\.
65 flags=BDFORhqu.> (optional)
67 Optional message processing flags. By default, a message is
68 copied unchanged.
69 B Append a blank line at the end of each message. This is
71 required by some mail user agents that recognize "From "
72 lines only when preceded by a blank line.
73 D Prepend a "Delivered-To: recipient" message header with
75 the envelope recipient address. Note: for this to work,
76 the transport_destination_recipient_limit must be 1.
77 This feature is available as of Postfix 2.0.
79 F Prepend a "From sender time_stamp" envelope header to the
81 message content. This is expected by, for example, UUCP
82 software.
83 O Prepend an "X-Original-To: recipient" message header with
85 the recipient address as given to Postfix. Note: for this
86 to work, the transport_destination_recipient_limit must
87 be 1.
88 This feature is available as of Postfix 2.0.
90 R Prepend a Return-Path: message header with the envelope
92 sender address.
93 h Fold the command-line $recipient domain name and $nexthop
95 host name to lower case. This is recommended for deliv‐
96 ery via UUCP.
97 q Quote white space and other special characters in the
99 command-line $sender and $recipient address localparts
100 (text to the left of the right-most @ character), accord‐
101 ing to an 8-bit transparent version of RFC 822. This is
102 recommended for delivery via UUCP or BSMTP.
103 The result is compatible with the address parsing of com‐
105 mand-line recipients by the Postfix sendmail(1) mail sub‐
106 mission command.
107 The q flag affects only entire addresses, not the partial
109 address information from the $user, $extension or $mail‐
110 box command-line macros.
111 u Fold the command-line $recipient address localpart (text
113 to the left of the right-most @ character) to lower case.
114 This is recommended for delivery via UUCP.
115 . Prepend "." to lines starting with ".". This is needed
117 by, for example, BSMTP software.
118 > Prepend ">" to lines starting with "From ". This is
120 expected by, for example, UUCP software.
121 null_sender=replacement (default: MAILER-DAEMON)
123 Replace the null sender address (typically used for delivery
124 status notifications) with the specified text when expanding the
125 $sender command-line macro, and when generating a From_ or
126 Return-Path: message header.
127 If the null sender replacement text is a non-empty string then
129 it is affected by the q flag for address quoting in command-line
130 arguments.
131 The null sender replacement text may be empty; this form is rec‐
133 ommended for content filters that feed mail back into Postfix.
134 The empty sender address is not affected by the q flag for
135 address quoting in command-line arguments.
136 Caution: a null sender address is easily mis-parsed by naive
138 software. For example, when the pipe(8) daemon executes a com‐
139 mand such as:
140 command -f$sender -- $recipient (bad)
142 the command will mis-parse the -f option value when the sender
144 address is a null string. For correct parsing, specify $sender
145 as an argument by itself:
146 command -f $sender -- $recipient (good)
148 This feature is available with Postfix 2.3 and later.
150 size=size_limit (optional)
152 Messages greater in size than this limit (in bytes) will be
153 returned to the sender as undeliverable.
154 user=username (required)
156 user=username:groupname
158 Execute the external command with the rights of the specified
159 username. The software refuses to execute commands with root
160 privileges, or with the privileges of the mail system owner. If
161 groupname is specified, the corresponding group ID is used
162 instead of the group ID of username.
163 argv=command... (required)
165 The command to be executed. This must be specified as the last
166 command attribute. The command is executed directly, i.e. with‐
167 out interpretation of shell meta characters by a shell command
168 interpreter.
169 In the command argument vector, the following macros are recog‐
171 nized and replaced with corresponding information from the Post‐
172 fix queue manager delivery request.
173 In addition to the form ${name}, the forms $name and $(name) are
175 also recognized. Specify $$ where a single $ is wanted.
176 ${client_address}
178 This macro expands to the remote client network address.
179 This is available in Postfix 2.2 and later.
181 ${client_helo}
183 This macro expands to the remote client HELO command
184 parameter.
185 This is available in Postfix 2.2 and later.
187 ${client_hostname}
189 This macro expands to the remote client hostname.
190 This is available in Postfix 2.2 and later.
192 ${client_protocol}
194 This macro expands to the remote client protocol.
195 This is available in Postfix 2.2 and later.
197 ${extension}
199 This macro expands to the extension part of a recipient
200 address. For example, with an address user+foo@domain
201 the extension is foo.
202 A command-line argument that contains ${extension}
204 expands into as many command-line arguments as there are
205 recipients.
206 This information is modified by the u flag for case fold‐
208 ing.
209 ${mailbox}
211 This macro expands to the complete local part of a recip‐
212 ient address. For example, with an address
213 user+foo@domain the mailbox is user+foo.
214 A command-line argument that contains ${mailbox} expands
216 to as many command-line arguments as there are recipi‐
217 ents.
218 This information is modified by the u flag for case fold‐
220 ing.
221 ${nexthop}
223 This macro expands to the next-hop hostname.
224 This information is modified by the h flag for case fold‐
226 ing.
227 ${recipient}
229 This macro expands to the complete recipient address.
230 A command-line argument that contains ${recipient}
232 expands to as many command-line arguments as there are
233 recipients.
234 This information is modified by the hqu flags for quoting
236 and case folding.
237 ${sasl_method}
239 This macro expands to the SASL authentication mechanism
240 used during the reception of the message. An empty string
241 is passed if the message has been received without SASL
242 authentication.
243 This is available in Postfix 2.2 and later.
245 ${sasl_sender}
247 This macro expands to the SASL sender name (i.e. the
248 original submitter as per RFC 2554) used during the
249 reception of the message.
250 This is available in Postfix 2.2 and later.
252 ${sasl_username}
254 This macro expands to the SASL user name used during the
255 reception of the message. An empty string is passed if
256 the message has been received without SASL authentica‐
257 tion.
258 This is available in Postfix 2.2 and later.
260 ${sender}
262 This macro expands to the envelope sender address. By
263 default, the null sender address expands to MAILER-DAE‐
264 MON; this can be changed with the null_sender attribute,
265 as described above.
266 This information is modified by the q flag for quoting.
268 ${size}
270 This macro expands to Postfix's idea of the message size,
271 which is an approximation of the size of the message as
272 delivered.
273 ${user}
275 This macro expands to the username part of a recipient
276 address. For example, with an address user+foo@domain
277 the username part is user.
278 A command-line argument that contains ${user} expands
280 into as many command-line arguments as there are recipi‐
281 ents.
282 This information is modified by the u flag for case fold‐
284 ing.
285
287 RFC 3463 (Enhanced status codes)
288
290 Command exit status codes are expected to follow the conventions
291 defined in <sysexits.h>. Exit status 0 means normal successful comple‐
292 tion.
293 Postfix version 2.3 and later support RFC 3463-style enhanced status
295 codes. If a command terminates with a non-zero exit status, and the
296 command output begins with an enhanced status code, this status code
297 takes precedence over the non-zero exit status.
298 Problems and transactions are logged to syslogd(8). Corrupted message
300 files are marked so that the queue manager can move them to the corrupt
301 queue for further inspection.
302
304 This program needs a dual personality 1) to access the private Postfix
305 queue and IPC mechanisms, and 2) to execute external commands as the
306 specified user. It is therefore security sensitive.
307
309 Changes to main.cf are picked up automatically as pipe(8) processes run
310 for only a limited amount of time. Use the command "postfix reload" to
311 speed up a change.
312 The text below provides only a parameter summary. See postconf(5) for
314 more details including examples.
315
317 In the text below, transport is the first field in a master.cf entry.
318 transport_destination_concurrency_limit ($default_destination_concur‐
320 rency_limit)
321 Limit the number of parallel deliveries to the same destination,
322 for delivery via the named transport. The limit is enforced by
323 the Postfix queue manager.
324 transport_destination_recipient_limit ($default_destination_recipi‐
326 ent_limit)
327 Limit the number of recipients per message delivery, for deliv‐
328 ery via the named transport. The limit is enforced by the Post‐
329 fix queue manager.
330 transport_time_limit ($command_time_limit)
332 Limit the time for delivery to external command, for delivery
333 via the named transport. The limit is enforced by the pipe
334 delivery agent.
335 Postfix 2.4 and later support a suffix that specifies the time
337 unit: s (seconds), m (minutes), h (hours), d (days), w (weeks).
338 The default time unit is seconds.
339
341 config_directory (see 'postconf -d' output)
342 The default location of the Postfix main.cf and master.cf con‐
343 figuration files.
344 daemon_timeout (18000s)
346 How much time a Postfix daemon process may take to handle a
347 request before it is terminated by a built-in watchdog timer.
348 delay_logging_resolution_limit (2)
350 The maximal number of digits after the decimal point when log‐
351 ging sub-second delay values.
352 export_environment (see 'postconf -d' output)
354 The list of environment variables that a Postfix process will
355 export to non-Postfix processes.
356 ipc_timeout (3600s)
358 The time limit for sending or receiving information over an
359 internal communication channel.
360 mail_owner (postfix)
362 The UNIX system account that owns the Postfix queue and most
363 Postfix daemon processes.
364 max_idle (100s)
366 The maximum amount of time that an idle Postfix daemon process
367 waits for an incoming connection before terminating voluntarily.
368 max_use (100)
370 The maximal number of incoming connections that a Postfix daemon
371 process will service before terminating voluntarily.
372 process_id (read-only)
374 The process ID of a Postfix command or daemon process.
375 process_name (read-only)
377 The process name of a Postfix command or daemon process.
378 queue_directory (see 'postconf -d' output)
380 The location of the Postfix top-level queue directory.
381 recipient_delimiter (empty)
383 The separator between user names and address extensions
384 (user+foo).
385 syslog_facility (mail)
387 The syslog facility of Postfix logging.
388 syslog_name (postfix)
390 The mail system name that is prepended to the process name in
391 syslog records, so that "smtpd" becomes, for example, "post‐
392 fix/smtpd".
393
395 qmgr(8), queue manager
396 bounce(8), delivery status reports
397 postconf(5), configuration parameters
398 master(5), generic daemon options
399 master(8), process manager
400 syslogd(8), system logging
401
403 The Secure Mailer license must be distributed with this software.
404
406 Wietse Venema
407 IBM T.J. Watson Research
408 P.O. Box 704
409 Yorktown Heights, NY 10598, USA
410 PIPE(8)