1FETCHMAIL(1) fetchmail reference manual FETCHMAIL(1)
2
6 fetchmail - fetch mail from a POP, IMAP, ETRN, or ODMR-capable server
7
10 fetchmail [option...] [mailserver...]
11 fetchmailconf
12
15 fetchmail is a mail-retrieval and forwarding utility; it fetches mail
16 from remote mail servers and forwards it to your local (client) ma‐
17 chine's delivery system. You can then handle the retrieved mail using
18 normal mail user agents such as mutt(1), elm(1) or Mail(1). The fetch‐
19 mail utility can be run in a daemon mode to repeatedly poll one or more
20 systems at a specified interval.
21 The fetchmail program can gather mail from servers supporting any of
23 the common mail-retrieval protocols: POP2 (legacy, to be removed from
24 future release), POP3, IMAP2bis, IMAP4, and IMAP4rev1. It can also use
25 the ESMTP ETRN extension and ODMR. (The RFCs describing all these pro‐
26 tocols are listed at the end of this manual page.)
27 While fetchmail is primarily intended to be used over on-demand TCP/IP
29 links (such as SLIP or PPP connections), it may also be useful as a
30 message transfer agent for sites which refuse for security reasons to
31 permit (sender-initiated) SMTP transactions with sendmail.
32
35 For troubleshooting, tracing and debugging, you need to increase fetch‐
36 mail's verbosity to actually see what happens. To do that, please run
37 both of the two following commands, adding all of the options you'd
38 normally use.
39 env LC_ALL=C fetchmail -V -v --nodetach --nosyslog
42 (This command line prints in English how fetchmail understands
44 your configuration.)
45 env LC_ALL=C fetchmail -vvv --nodetach --nosyslog
48 (This command line actually runs fetchmail with verbose English
50 output.)
51 Also see item #G3 in fetchmail's FAQ
53 ⟨https://fetchmail.sourceforge.io/fetchmail-FAQ.html#G3⟩.
54 You can omit the LC_ALL=C part above if you want output in the local
56 language (if supported). However if you are posting to mailing lists,
57 please leave it in. The maintainers do not necessarily understand your
58 language, please use English.
59
62 Your fetchmail distribution should have come with a README.SSL file,
63 which see. It is recommended to configure all polls with --ssl --ssl‐
64 proto tls1.2+ if supported by the server, which configures fetchmail
65 along recent IETF proposed standards and best current practices,
66 RFC-8314, RFC-8996, RFC-8997.
67
70 If fetchmail is used with a POP or an IMAP server (but not with ETRN or
71 ODMR), it has two fundamental modes of operation for each user account
72 from which it retrieves mail: singledrop- and multidrop-mode.
73 In singledrop-mode,
75 fetchmail assumes that all messages in the user's account (mail‐
76 box) are intended for a single recipient. The identity of the
77 recipient will either default to the local user currently exe‐
78 cuting fetchmail, or will need to be explicitly specified in the
79 configuration file.
80 fetchmail uses singledrop-mode when the fetchmailrc configura‐
82 tion contains at most a single local user specification for a
83 given server account.
84 In multidrop-mode,
86 fetchmail assumes that the mail server account actually contains
87 mail intended for any number of different recipients. There‐
88 fore, fetchmail must attempt to deduce the proper "envelope re‐
89 cipient" from the mail headers of each message. In this mode of
90 operation, fetchmail almost resembles a mail transfer agent
91 (MTA).
92 Note that neither the POP nor IMAP protocols were intended for
94 use in this fashion, and hence envelope information is often not
95 directly available. The ISP must store the envelope information
96 in some message header and. The ISP must also store one copy of
97 the message per recipient. If either of the conditions is not
98 fulfilled, this process is unreliable, because fetchmail must
99 then resort to guessing the true envelope recipient(s) of a mes‐
100 sage. This usually fails for mailing list messages and Bcc:d
101 mail, or mail for multiple recipients in your domain.
102 fetchmail uses multidrop-mode when more than one local user
104 and/or a wildcard is specified for a particular server account
105 in the configuration file.
106 In ETRN and ODMR modes,
108 these considerations do not apply, as these protocols are based
109 on SMTP, which provides explicit envelope recipient information.
110 These protocols always support multiple recipients.
111 As each message is retrieved, fetchmail normally delivers it via SMTP
113 to port 25 on the machine it is running on (localhost), just as though
114 it were being passed in over a normal TCP/IP link. fetchmail provides
115 the SMTP server with an envelope recipient derived in the manner de‐
116 scribed previously. The mail will then be delivered according to your
117 MTA's rules (the Mail Transfer Agent is usually sendmail(8), exim(8),
118 or postfix(8)). Invoking your system's MDA (Mail Delivery Agent) is
119 the duty of your MTA. All the delivery-control mechanisms (such as
120 .forward files) normally available through your system MTA and local
121 delivery agents will therefore be applied as usual.
122 If your fetchmail configuration sets a local MDA (see the --mda op‐
124 tion), it will be used directly instead of talking SMTP to port 25.
125 If the program fetchmailconf is available, it will assist you in set‐
127 ting up and editing a fetchmailrc configuration. It runs under the X
128 window system and requires that the language Python and the Tk toolkit
129 (with Python bindings) be present on your system. If you are first
130 setting up fetchmail for single-user mode, it is recommended that you
131 use Novice mode. Expert mode provides complete control of fetchmail
132 configuration, including the multidrop features. In either case, the
133 'Autoprobe' button will tell you the most capable protocol a given mail
134 server supports, and warn you of potential problems with that server.
135
138 Fetchmail's run-time strings have been translated (localized) to some
139 languages, but the manual is only available in English. In some situa‐
140 tions, for comparing output to manual, it may be helpful to switch
141 fetchmail to English output by overriding the locale variables, for in‐
142 stance:
143 env LC_ALL=C fetchmail # add other options before the hash
146 env LANG=en fetchmail # other options before the hash
149 or similar. Details vary by operating system.
151
154 The behavior of fetchmail is controlled by command-line options and a
155 run control file, ~/.fetchmailrc, the syntax of which we describe in a
156 later section (this file is what the fetchmailconf program edits).
157 Command-line options override ~/.fetchmailrc declarations.
158 Each server name that you specify following the options on the command
160 line will be queried. If you do not specify any servers on the command
161 line, each 'poll' entry in your ~/.fetchmailrc file will be queried,
162 unless the idle option is used, which see.
163 To facilitate the use of fetchmail in scripts and pipelines, it returns
165 an appropriate exit code upon termination -- see EXIT CODES below.
166 The following options modify the behavior of fetchmail. It is seldom
168 necessary to specify any of these once you have a working .fetchmailrc
169 file set up.
170 Almost all options have a corresponding keyword which can be used to
172 declare them in a .fetchmailrc file.
173 Some special options are not covered here, but are documented instead
175 in sections on AUTHENTICATION and DAEMON MODE which follow.
176 General Options
178 -? | --help
179 Displays option help.
180 -V | --version
182 Displays the version information for your copy of fetchmail. No
183 mail fetch is performed. Instead, for each server specified,
184 all the option information that would be computed if fetchmail
185 were connecting to that server is displayed. Any non-printable
186 characters in passwords or other string names are shown as back-
187 slashed C-like escape sequences. This option is useful for ver‐
188 ifying that your options are set the way you want them.
189 -c | --check
191 Return a status code to indicate whether there is mail waiting,
192 without actually fetching or deleting mail (see EXIT CODES be‐
193 low). This option turns off daemon mode (in which it would be
194 useless). It does not play well with queries to multiple sites,
195 and does not work with ETRN or ODMR. It will return a false
196 positive if you leave read but undeleted mail in your server
197 mailbox and your fetch protocol cannot tell kept messages from
198 new ones. This means it will work with IMAP, not work with
199 POP2, and may occasionally flake out under POP3.
200 -s | --silent
202 Silent mode. Suppresses all progress/status messages that are
203 normally echoed to standard output during a fetch (but does not
204 suppress actual error messages). The --verbose option overrides
205 this.
206 -v | --verbose
208 Verbose mode. All control messages passed between fetchmail and
209 the mail server are echoed to stdout. Overrides --silent. Dou‐
210 bling this option (-v -v) causes extra diagnostic information to
211 be printed.
212 --nosoftbounce
214 (since v6.3.10, Keyword: set no softbounce, since v6.3.10)
215 Hard bounce mode. All permanent delivery errors cause messages
216 to be deleted from the upstream server, see "no softbounce" be‐
217 low.
218 --softbounce
220 (since v6.3.10, Keyword: set softbounce, since v6.3.10)
221 Soft bounce mode. All permanent delivery errors cause messages
222 to be left on the upstream server if the protocol supports that.
223 This option is on by default to match historic fetchmail docu‐
224 mentation, and will be changed to hard bounce mode in the next
225 fetchmail release.
226 Disposal Options
228 -a | --all | (since v6.3.3) --fetchall
229 (Keyword: fetchall, since v3.0)
230 Retrieve both old (seen) and new messages from the mail server.
231 The default is to fetch only messages the server has not marked
232 seen. Under POP3, this option also forces the use of RETR
233 rather than TOP. Note that POP2 retrieval behaves as though
234 --all is always on (see RETRIEVAL FAILURE MODES below) and this
235 option does not work with ETRN or ODMR. While the -a and --all
236 command-line and fetchall rcfile options have been supported for
237 a long time, the --fetchall command-line option was added in
238 v6.3.3.
239 -k | --keep
241 (Keyword: keep)
242 Keep retrieved messages on the remote mail server. Normally,
243 messages are deleted from the folder on the mail server after
244 they have been retrieved. Specifying the keep option causes re‐
245 trieved messages to remain in your folder on the mail server.
246 This option does not work with ETRN or ODMR. If used with POP3,
247 it is recommended to also specify the --uidl option or uidl key‐
248 word.
249 -K | --nokeep
251 (Keyword: nokeep)
252 Delete retrieved messages from the remote mail server. This op‐
253 tion forces retrieved mail to be deleted. It may be useful if
254 you have specified a default of keep in your .fetchmailrc. This
255 option is forced on with ETRN and ODMR.
256 -F | --flush
258 (Keyword: flush)
259 POP3/IMAP only. This is a dangerous option and can cause mail
260 loss when used improperly. It deletes old (seen) messages from
261 the mail server before retrieving new messages. Warning: This
262 can cause mail loss if you check your mail with other clients
263 than fetchmail, and cause fetchmail to delete a message it had
264 never fetched before. It can also cause mail loss if the mail
265 server marks the message seen after retrieval (IMAP2 servers).
266 You should probably not use this option in your configuration
267 file. If you use it with POP3, you must use the 'uidl' option.
268 What you probably want is the default setting: if you do not
269 specify '-k', then fetchmail will automatically delete messages
270 after successful delivery.
271 --limitflush
273 POP3/IMAP only, since version 6.3.0. Delete oversized messages
274 from the mail server before retrieving new messages. The size
275 limit should be separately specified with the --limit option.
276 This option does not work with ETRN or ODMR.
277 Protocol and Query Options
279 -p <proto> | --proto <proto> | --protocol <proto>
280 (Keyword: proto[col])
281 Specify the protocol to use when communicating with the remote
282 mail server. If no protocol is specified, the default is AUTO.
283 proto may be one of the following:
284 AUTO Tries IMAP, POP3, and POP2 (skipping any of these for
286 which support has not been compiled in).
287 POP2 Post Office Protocol 2 (legacy, to be removed from future
289 release)
290 POP3 Post Office Protocol 3
292 APOP Use POP3 with old-fashioned MD5-challenge authentication.
294 Considered not resistant to man-in-the-middle attacks.
295 RPOP Use POP3 with RPOP authentication.
297 KPOP Use POP3 with Kerberos V4 authentication on port 1109.
299 SDPS Use POP3 with Demon Internet's SDPS extensions.
301 IMAP IMAP2bis, IMAP4, or IMAP4rev1 (fetchmail automatically
303 detects their capabilities).
304 ETRN Use the ESMTP ETRN option.
306 ODMR Use the On-Demand Mail Relay ESMTP profile.
308 All these alternatives work in basically the same way (communicating
310 with standard server daemons to fetch mail already delivered to a mail‐
311 box on the server) except ETRN and ODMR. The ETRN mode allows you to
312 ask a compliant ESMTP server (such as BSD sendmail at release 8.8.0 or
313 higher) to immediately open a sender-SMTP connection to your client ma‐
314 chine and begin forwarding any items addressed to your client machine
315 in the server's queue of undelivered mail. The ODMR mode requires an
316 ODMR-capable server and works similarly to ETRN, except that it does
317 not require the client machine to have a static DNS.
318 -U | --uidl
320 (Keyword: uidl)
321 Force UIDL use (effective only with POP3). Force client-side
322 tracking of 'newness' of messages (UIDL stands for "unique ID
323 listing" and is described in RFC1939). Use with 'keep' to use a
324 mailbox as a baby news drop for a group of users. The fact that
325 seen messages are skipped is logged, unless error logging is
326 done through syslog while running in daemon mode. Note that
327 fetchmail may automatically enable this option depending on up‐
328 stream server capabilities. Note also that this option may be
329 removed and forced enabled in a future fetchmail version. See
330 also: --idfile.
331 --idle (since 6.3.3)
333 (Keyword: idle, since before 6.0.0)
334 Enable IDLE use (effective only with IMAP). Note that this works
335 with only one account and one folder at a given time, other
336 folders or accounts will not be polled when idle is in effect!
337 While the idle rcfile keyword had been supported for a long
338 time, the --idle command-line option was added in version 6.3.3.
339 IDLE use means that fetchmail tells the IMAP server to send no‐
340 tice of new messages, so they can be retrieved sooner than would
341 be possible with regular polls.
342 -P <portnumber> | --service <servicename>
344 (Keyword: service) Since version 6.3.0.
345 The service option permits you to specify a service name to con‐
346 nect to. You can specify a decimal port number here, if your
347 services database lacks the required service-port assignments.
348 See the FAQ item R12 and the --ssl documentation for details.
349 This replaces the older --port option.
350 Note that this does not magically switch between TLS-wrapped and START‐
352 TLS modes, if you specify a port number or service name here that is
353 TLS-wrapped, meaning it starts to negotiate TLS before sending applica‐
354 tion data in the clear, you may need to specify --ssl on the command
355 line or ssl in your rcfile.
356 --port <portnumber>
358 (Keyword: port)
359 Obsolete version of --service that does not take service names.
360 Note: this option may be removed from a future version.
361 --principal <principal>
363 (Keyword: principal)
364 The principal option permits you to specify a service principal
365 for mutual authentication. This is applicable to POP3 or IMAP
366 with Kerberos 4 authentication only. It does not apply to Ker‐
367 beros 5 or GSSAPI. This option may be removed in a future
368 fetchmail version.
369 -t <seconds> | --timeout <seconds>
371 (Keyword: timeout)
372 The timeout option allows you to set a server-non-response time‐
373 out in seconds. If a mail server does not send a greeting mes‐
374 sage or respond to commands for the given number of seconds,
375 fetchmail will drop the connection to it. Without such a time‐
376 out fetchmail might hang until the TCP connection times out,
377 trying to fetch mail from a down host, which may be very long.
378 This would be particularly annoying for a fetchmail running in
379 the background. There is a default timeout which fetchmail -V
380 will report. If a given connection receives too many timeouts
381 in succession, fetchmail will consider it wedged and stop retry‐
382 ing. The calling user will be notified by email if this hap‐
383 pens.
384 Beginning with fetchmail 6.3.10, the SMTP client uses the recom‐
386 mended minimum timeouts from RFC-5321 while waiting for the
387 SMTP/LMTP server it is talking to. You can raise the timeouts
388 even more, but you cannot shorten them. This is to avoid a
389 painful situation where fetchmail has been configured with a
390 short timeout (a minute or less), ships a long message (many
391 MBytes) to the local MTA, which then takes longer than timeout
392 to respond "OK", which it eventually will; that would mean the
393 mail gets delivered properly, but fetchmail cannot notice it and
394 will thus re-fetch this big message over and over again.
395 --plugin <command>
397 (Keyword: plugin)
398 The plugin option allows you to use an external program to es‐
399 tablish the TCP connection. This is useful if you want to use
400 ssh, or need some special firewall setup. The program will be
401 looked up in $PATH and can optionally be passed the host name
402 and port as arguments using "%h" and "%p" respectively (note
403 that the interpolation logic is rather primitive, and these to‐
404 kens must be bounded by whitespace or beginning of string or end
405 of string). Fetchmail will write to the plugin's stdin and read
406 from the plugin's stdout.
407 --plugout <command>
409 (Keyword: plugout)
410 Identical to the plugin option above, but this one is used for
411 the SMTP connections.
412 -r <name> | --folder <name>
414 (Keyword: folder[s])
415 Causes a specified non-default mail folder on the mail server
416 (or comma-separated list of folders) to be retrieved. The syn‐
417 tax of the folder name is server-dependent. This option is not
418 available under POP3, ETRN, or ODMR.
419 --tracepolls
421 (Keyword: tracepolls)
422 Tell fetchmail to poll trace information in the form 'polling
423 account %s' and 'folder %s' to the Received line it generates,
424 where the %s parts are replaced by the user's remote name, the
425 poll label, and the folder (mailbox) where available (the Re‐
426 ceived header also normally includes the server's true name).
427 This can be used to facilitate mail filtering based on the ac‐
428 count it is being received from. The folder information is writ‐
429 ten only since version 6.3.4.
430 --ssl (Keyword: ssl)
432 Causes the connection to the mail server to be encrypted via
433 SSL, by negotiating SSL directly after connecting (called SSL-
434 wrapped mode, or Implicit TLS by RFC-8314). Please see the de‐
435 scription of --sslproto below! More information is available in
436 the README.SSL file that ships with fetchmail.
437 Note that even if this option is omitted, fetchmail may still
439 negotiate SSL in-band for POP3 or IMAP, through the STLS or
440 STARTTLS feature. You can use the --sslproto option to modify
441 that behavior.
442 If no port is specified, the connection is attempted to the well
444 known port of the SSL version of the base protocol. This is
445 generally a different port than the port used by the base proto‐
446 col. For IMAP, this is port 143 for the clear protocol and port
447 993 for the SSL secured protocol; for POP3, it is port 110 for
448 the clear text and port 995 for the encrypted variant.
449 If your system lacks the corresponding entries from /etc/ser‐
451 vices, see the --service option and specify the numeric port
452 number as given in the previous paragraph (unless your ISP had
453 directed you to different ports, which is uncommon however).
454 --sslcert <name>
456 (Keyword: sslcert)
457 For certificate-based client authentication. Some SSL encrypted
458 servers require client side keys and certificates for authenti‐
459 cation. In most cases, this is optional. This specifies the
460 location of the public key certificate to be presented to the
461 server at the time the SSL session is established. It is not
462 required (but may be provided) if the server does not require
463 it. It may be the same file as the private key (combined key
464 and certificate file) but this is not recommended. Also see
465 --sslkey below.
466 NOTE: If you use client authentication, the user name is fetched
468 from the certificate's CommonName and overrides the name set
469 with --user.
470 --sslkey <name>
472 (Keyword: sslkey)
473 Specifies the file name of the client side private SSL key.
474 Some SSL encrypted servers require client side keys and certifi‐
475 cates for authentication. In most cases, this is optional.
476 This specifies the location of the private key used to sign
477 transactions with the server at the time the SSL session is es‐
478 tablished. It is not required (but may be provided) if the
479 server does not require it. It may be the same file as the pub‐
480 lic key (combined key and certificate file) but this is not rec‐
481 ommended.
482 If a password is required to unlock the key, it will be prompted
484 for at the time just prior to establishing the session to the
485 server. This can cause some complications in daemon mode.
486 Also see --sslcert above.
488 --sslproto <value>
490 (Keyword: sslproto, NOTE: semantic changes since v6.4.0)
491 This option has a dual use, out of historic fetchmail behaviour.
492 It controls both the SSL/TLS protocol version and, if --ssl is
493 not specified, the STARTTLS behaviour (upgrading the protocol to
494 an SSL or TLS connection in-band). Some other options may how‐
495 ever make TLS mandatory.
496 Only if this option and --ssl are both missing for a poll, there
498 will be opportunistic TLS for POP3 and IMAP, where fetchmail
499 will attempt to upgrade to TLSv1 or newer.
500 Recognized values for --sslproto are given below. You should
502 normally choose one of the auto-negotiating options, i. e.
503 'tls1.2+' or 'auto' or one of the other options ending in a plus
504 (+) character. Note that depending on OpenSSL library version
505 and configuration, some options cause run-time errors because
506 the requested SSL or TLS versions are not supported by the par‐
507 ticular installed OpenSSL library.
508 'TLS1.2+'
510 (recommended). Since v6.4.0. Require TLS. Auto-negotiate
511 TLSv1.2 or newer.
512 'auto' (default). Since v6.4.0. Require TLS. Auto-negotiate
514 TLSv1 or newer, disable SSLv3 downgrade. (fetchmail
515 6.3.26 and older have auto-negotiated all protocols that
516 their OpenSSL library supported, including the broken
517 SSLv3).
518 '', the empty string
520 Disable STARTTLS. If --ssl is given for the same server,
521 log an error and pretend that 'auto' had been used in‐
522 stead.
523 'SSL23'
525 see 'auto'.
526 'SSL3' Require SSLv3 exactly. SSLv3 is broken, not supported on
528 all systems, avoid it if possible. This will make fetch‐
529 mail negotiate SSLv3 only, and is the only way besides
530 'SSL3+' to have fetchmail 6.4.0 or newer permit SSLv3.
531 'SSL3+'
533 same as 'auto', but permit SSLv3 as well. This is the
534 only way besides 'SSL3' to have fetchmail 6.4.0 or newer
535 permit SSLv3.
536 'TLS1' Require TLSv1. This does not negotiate TLSv1.1 or newer,
538 and is discouraged. Replace by TLS1+ unless the latter
539 chokes your server.
540 'TLS1+'
542 Since v6.4.0. See 'auto'.
543 'TLS1.1'
545 Since v6.4.0. Require TLS v1.1 exactly.
546 'TLS1.1+'
548 Since v6.4.0. Require TLS. Auto-negotiate TLSv1.1 or
549 newer.
550 'TLS1.2'
552 Since v6.4.0. Require TLS v1.2 exactly.
553 'TLS1.3'
555 Since v6.4.0. Require TLS v1.3 exactly.
556 'TLS1.3+'
558 Since v6.4.0. Require TLS. Auto-negotiate TLSv1.3 or
559 newer.
560 Unrecognized parameters
562 are treated the same as 'auto'.
563 NOTE: you should hardly ever need to use anything other than ''
565 (to force an unencrypted connection) or 'auto' (to enforce TLS).
566 --sslcertck
568 (Keyword: sslcertck, default enabled since v6.4.0)
569 --sslcertck causes fetchmail to require that SSL/TLS be used and
570 disconnect unless it can successfully negotiate SSL or TLS, or
571 if it cannot successfully verify and validate the certificate
572 and follow it to a trust anchor (or trusted root certificate).
573 The trust anchors are given as a set of local trusted certifi‐
574 cates (see the sslcertfile and sslcertpath options). If the
575 server certificate cannot be obtained or is not signed by one of
576 the trusted ones (directly or indirectly), fetchmail will dis‐
577 connect, regardless of the sslfingerprint option.
578 --nosslcertck
580 (Keyword: no sslcertck, only in v6.4.X)
581 The opposite of --sslcertck, this is a discouraged option. It
582 permits fetchmail to continue connecting even if the server cer‐
583 tificate failed the verification checks. Should only be used
584 together with --sslfingerprint.
585 --sslcertfile <file>
587 (Keyword: sslcertfile, since v6.3.17)
588 Sets the file fetchmail uses to look up local certificates. The
589 default is empty. This can be given in addition to --sslcert‐
590 path below, and certificates specified in --sslcertfile will be
591 processed before those in --sslcertpath. The option can be used
592 in addition to --sslcertpath.
593 The file is a text file. It contains the concatenation of
595 trusted CA certificates in PEM format.
596 Note that using this option will suppress loading the default
598 SSL trusted CA certificates file unless you set the environment
599 variable FETCHMAIL_INCLUDE_DEFAULT_X509_CA_CERTS to a non-empty
600 value.
601 --sslcertpath <directory>
603 (Keyword: sslcertpath)
604 Sets the directory fetchmail uses to look up local certificates.
605 The default is your OpenSSL default directory. The directory
606 must be hashed the way OpenSSL expects it - every time you add
607 or modify a certificate in the directory, you need to use the
608 c_rehash tool (which comes with OpenSSL in the tools/ sub-direc‐
609 tory). Also, after OpenSSL upgrades, you may need to run c_re‐
610 hash.
611 This can be given in addition to --sslcertfile above, which see
613 for precedence rules.
614 Note that using this option will suppress adding the default SSL
616 trusted CA certificates directory unless you set the environment
617 variable FETCHMAIL_INCLUDE_DEFAULT_X509_CA_CERTS to a non-empty
618 value.
619 --sslcommonname <common name>
621 (Keyword: sslcommonname; since v6.3.9)
622 Use of this option is discouraged. Before using it, contact the
623 administrator of your upstream server and ask for a proper SSL
624 certificate to be used. If that cannot be attained, this option
625 can be used to specify the name (CommonName) that fetchmail ex‐
626 pects on the server certificate. A correctly configured server
627 will have this set to the host name by which it is reached, and
628 by default fetchmail will expect as much. Use this option when
629 the CommonName is set to some other value, to avoid the "Server
630 CommonName mismatch" warning, and only if the upstream server's
631 operator cannot be made to use proper certificates.
632 --sslfingerprint <fingerprint>
634 (Keyword: sslfingerprint)
635 Specify the fingerprint of the server key (an MD5 hash of the
636 key) in hexadecimal notation with colons separating groups of
637 two digits. The letter hex digits must be in upper case. This is
638 the format that fetchmail uses to report the fingerprint when an
639 SSL connection is established. When this is specified, fetchmail
640 will compare the server key fingerprint with the given one, and
641 the connection will fail if they do not match, regardless of the
642 sslcertck setting. The connection will also fail if fetchmail
643 cannot obtain an SSL certificate from the server. This can be
644 used to prevent man-in-the-middle attacks, but the finger print
645 from the server must be obtained or verified over a secure chan‐
646 nel, and certainly not over the same Internet connection that
647 fetchmail would use.
648 Using this option will prevent printing certificate verification
650 errors as long as --nosslcertck is in effect.
651 To obtain the fingerprint of a certificate stored in the file
653 cert.pem, try:
654 openssl x509 -in cert.pem -noout -md5 -fingerprint
656 For details, see x509(1ssl).
658 Delivery Control Options
660 -S <hosts> | --smtphost <hosts>
661 (Keyword: smtp[host])
662 Specify a hunt list of hosts to forward mail to (one or more
663 host names, comma-separated). Hosts are tried in list order; the
664 first one that is up becomes the forwarding target for the cur‐
665 rent run. If this option is not specified, 'localhost' is used
666 as the default. Each host name may have a port number following
667 the host name. The port number is separated from the host name
668 by a slash; the default port is "smtp". If you specify an abso‐
669 lute path name (beginning with a /), it will be interpreted as
670 the name of a UNIX socket accepting LMTP connections (such as is
671 supported by the Cyrus IMAP daemon) Example:
672 --smtphost server1,server2/2525,server3,/var/imap/socket/lmtp
674 This option can be used with ODMR, and will make fetchmail a re‐
676 lay between the ODMR server and SMTP or LMTP receiver.
677 WARNING: if you use address numeric IP addresses here, be sure
679 to use --smtpaddress or --smtpname (either of which see) with a
680 valid SMTP address literal!
681 --fetchdomains <hosts>
683 (Keyword: fetchdomains)
684 In ETRN or ODMR mode, this option specifies the list of domains
685 the server should ship mail for once the connection is turned
686 around. The default is the FQDN of the machine running fetch‐
687 mail.
688 -D <domain> | --smtpaddress <domain>
690 (Keyword: smtpaddress)
691 Specify the domain to be appended to addresses in RCPT TO lines
692 shipped to SMTP. When this is not specified, the name of the
693 SMTP server (as specified by --smtphost) is used for SMTP/LMTP
694 and 'localhost' is used for UNIX socket/BSMTP.
695 NOTE: if you intend to use numeric addresses, or so-called ad‐
697 dress literals per the SMTP standard, write them in proper SMTP
698 syntax, for instance --smtpaddress "[192.0.2.6]" or --smtpad‐
699 dress "[IPv6:2001:DB8::6]".
700 --smtpname <user@domain>
702 (Keyword: smtpname)
703 Specify the domain and user to be put in RCPT TO lines shipped
704 to SMTP. The default user is the current local user. Please
705 also see the NOTE about --smtpaddress and address literals
706 above.
707 -Z <nnn> | --antispam <nnn[, nnn]...>
709 (Keyword: antispam)
710 Specifies the list of numeric SMTP errors that are to be inter‐
711 preted as a spam-block response from the listener. A value of
712 -1 disables this option. For the command-line option, the list
713 values should be comma-separated. Note that the antispam values
714 only apply to "MAIL FROM" responses in the SMTP/LMTP dialogue,
715 but several MTAs (Postfix in its default configuration, qmail)
716 defer the anti-spam response code until after the RCPT TO. --an‐
717 tispam does not work in these circumstances. Also see --soft‐
718 bounce (default) and its inverse.
719 -m <command> | --mda <command>
721 (Keyword: mda)
722 This option lets fetchmail use a Message or Local Delivery Agent
723 (MDA or LDA) directly, rather than forward via SMTP or LMTP.
724 To avoid losing mail, use this option only with MDAs like mail‐
726 drop or MTAs like sendmail that exit with a nonzero status on
727 disk-full and other delivery errors; the nonzero status tells
728 fetchmail that delivery failed and prevents the message from be‐
729 ing deleted on the server.
730 If fetchmail is running as root, it sets its user id while de‐
732 livering mail through an MDA as follows: First, the FETCH‐
733 MAILUSER, LOGNAME, and USER environment variables are checked in
734 this order. The value of the first variable from his list that
735 is defined (even if it is empty!) is looked up in the system
736 user database. If none of the variables is defined, fetchmail
737 will use the real user id it was started with. If one of the
738 variables was defined, but the user stated there is not found,
739 fetchmail continues running as root, without checking remaining
740 variables on the list. Practically, this means that if you run
741 fetchmail as root (not recommended), it is most useful to define
742 the FETCHMAILUSER environment variable to set the user that the
743 MDA should run as. Some MDAs (such as maildrop) are designed to
744 be setuid root and setuid to the recipient's user id, so you do
745 not lose functionality this way even when running fetchmail as
746 unprivileged user. Check the MDA's manual for details.
747 Some possible MDAs are "/usr/sbin/sendmail -i -f %F -- %T"
749 (Note: some several older or vendor sendmail versions mistake --
750 for an address, rather than an indicator to mark the end of the
751 option arguments), "/usr/bin/deliver" and "/usr/bin/maildrop -d
752 %T". Local delivery addresses will be inserted into the MDA
753 command wherever you place a %T; the mail message's From address
754 will be inserted where you place an %F.
755 Do NOT enclose the %F or %T string in single quotes! For both
757 %T and %F, fetchmail encloses the addresses in single quotes
758 ('), after removing any single quotes they may contain, before
759 the MDA command is passed to the shell.
760 Do NOT use an MDA invocation that dispatches on the contents of
762 To/Cc/Bcc, like "sendmail -i -t" or "qmail-inject", it will cre‐
763 ate mail loops and bring the just wrath of many postmasters down
764 upon your head. This is one of the most frequent configuration
765 errors!
766 Also, do not try to combine multidrop mode with an MDA such as
768 maildrop that can only accept one address, unless your upstream
769 stores one copy of the message per recipient and transports the
770 envelope recipient in a header; you will lose mail.
771 The well-known procmail(1) package is very hard to configure
773 properly, it has a very nasty "fall through to the next rule"
774 behavior on delivery errors (even temporary ones, such as out of
775 disk space if another user's mail daemon copies the mailbox
776 around to purge old messages), so your mail will end up in the
777 wrong mailbox sooner or later. The proper procmail configuration
778 is outside the scope of this document. Using maildrop(1) is usu‐
779 ally much easier, and many users find the filter syntax used by
780 maildrop easier to understand.
781 Finally, we strongly advise that you do not use qmail-inject.
783 The command line interface is non-standard without providing
784 benefits for typical use, and fetchmail makes no attempts to ac‐
785 commodate qmail-inject's deviations from the standard. Some of
786 qmail-inject's command-line and environment options are actually
787 dangerous and can cause broken threads, non-detected duplicate
788 messages and forwarding loops.
789 --lmtp (Keyword: lmtp)
792 Cause delivery via LMTP (Local Mail Transfer Protocol). A ser‐
793 vice host and port must be explicitly specified on each host in
794 the smtphost hunt list (see above) if this option is selected;
795 the default port 25 will (in accordance with RFC 2033) not be
796 accepted.
797 --bsmtp <filename>
799 (Keyword: bsmtp)
800 Append fetched mail to a BSMTP file. This simply contains the
801 SMTP commands that would normally be generated by fetchmail when
802 passing mail to an SMTP listener daemon.
803 An argument of '-' causes the SMTP batch to be written to stan‐
805 dard output, which is of limited use: this only makes sense for
806 debugging, because fetchmail's regular output is interspersed on
807 the same channel, so this is not suitable for mail delivery.
808 This special mode may be removed in a later release.
809 Note that fetchmail's reconstruction of MAIL FROM and RCPT TO
811 lines is not guaranteed correct; the caveats discussed under THE
812 USE AND ABUSE OF MULTIDROP MAILBOXES below apply. This mode has
813 precedence before --mda and SMTP/LMTP.
814 --bad-header {reject|accept}
816 (Keyword: bad-header; since v6.3.15)
817 Specify how fetchmail is supposed to treat messages with bad
818 headers, i.e., headers with bad syntax. Traditionally, fetchmail
819 has rejected such messages, but some distributors modified
820 fetchmail to accept them. You can now configure fetchmail's be‐
821 haviour per server.
822 Resource Limit Control Options
825 -l <maxbytes> | --limit <maxbytes>
826 (Keyword: limit)
827 Takes a maximum octet size argument, where 0 is the default and
828 also the special value designating "no limit". If nonzero, mes‐
829 sages larger than this size will not be fetched and will be left
830 on the server (in foreground sessions, the progress messages
831 will note that they are "oversized"). If the fetch protocol
832 permits (in particular, under IMAP or POP3 without the fetchall
833 option) the message will not be marked seen.
834 An explicit --limit of 0 overrides any limits set in your run
836 control file. This option is intended for those needing to
837 strictly control fetch time due to expensive and variable phone
838 rates.
839 Combined with --limitflush, it can be used to delete oversized
841 messages waiting on a server. In daemon mode, oversize notifi‐
842 cations are mailed to the calling user (see the --warnings op‐
843 tion). This option does not work with ETRN or ODMR.
844 -w <interval> | --warnings <interval>
846 (Keyword: warnings)
847 Takes an interval in seconds. When you call fetchmail with a
848 'limit' option in daemon mode, this controls the interval at
849 which warnings about oversized messages are mailed to the call‐
850 ing user (or the user specified by the 'postmaster' option).
851 One such notification is always mailed at the end of the first
852 poll that the oversized message is detected. Thereafter, re-no‐
853 tification is suppressed until after the warning interval
854 elapses (it will take place at the end of the first following
855 poll).
856 -b <count> | --batchlimit <count>
858 (Keyword: batchlimit)
859 Specify the maximum number of messages that will be shipped to
860 an SMTP listener before the connection is deliberately torn down
861 and rebuilt (defaults to 0, meaning no limit). An explicit
862 --batchlimit of 0 overrides any limits set in your run control
863 file. While sendmail(8) normally initiates delivery of a mes‐
864 sage immediately after receiving the message terminator, some
865 SMTP listeners are not so prompt. MTAs like smail(8) may wait
866 till the delivery socket is shut down to deliver. This may pro‐
867 duce annoying delays when fetchmail is processing very large
868 batches. Setting the batch limit to some nonzero size will pre‐
869 vent these delays. This option does not work with ETRN or ODMR.
870 -B <number> | --fetchlimit <number>
872 (Keyword: fetchlimit)
873 Limit the number of messages accepted from a given server in a
874 single poll. By default there is no limit. An explicit --fetch‐
875 limit of 0 overrides any limits set in your run control file.
876 This option does not work with ETRN or ODMR.
877 --fetchsizelimit <number>
879 (Keyword: fetchsizelimit)
880 Limit the number of sizes of messages accepted from a given
881 server in a single transaction. This option is useful in reduc‐
882 ing the delay in downloading the first mail when there are too
883 many mails in the mailbox. By default, the limit is 100. If
884 set to 0, sizes of all messages are downloaded at the start.
885 This option does not work with ETRN or ODMR. For POP3, the only
886 valid non-zero value is 1.
887 --fastuidl <number>
889 (Keyword: fastuidl)
890 Do a binary instead of linear search for the first unseen UID.
891 Binary search avoids downloading the UIDs of all mails. This
892 saves time (especially in daemon mode) where downloading the
893 same set of UIDs in each poll is a waste of bandwidth. The num‐
894 ber 'n' indicates how rarely a linear search should be done. In
895 daemon mode, linear search is used once followed by binary
896 searches in 'n-1' polls if 'n' is greater than 1; binary search
897 is always used if 'n' is 1; linear search is always used if 'n'
898 is 0. In non-daemon mode, binary search is used if 'n' is 1;
899 otherwise linear search is used. The default value of 'n' is 4.
900 This option works with POP3 only.
901 -e <count> | --expunge <count>
903 (Keyword: expunge)
904 Arrange for deletions to be made final after a given number of
905 messages. Under POP2 or POP3, fetchmail cannot make deletions
906 final without sending QUIT and ending the session -- with this
907 option on, fetchmail will break a long mail retrieval session
908 into multiple sub-sessions, sending QUIT after each sub-session.
909 This is a good defense against line drops on POP3 servers. Un‐
910 der IMAP, fetchmail normally issues an EXPUNGE command after
911 each deletion in order to force the deletion to be done immedi‐
912 ately. This is safest when your connection to the server is
913 flaky and expensive, as it avoids re-sending duplicate mail af‐
914 ter a line hit. However, on large mailboxes the overhead of re-
915 indexing after every message can slam the server pretty hard, so
916 if your connection is reliable it is good to do expunges less
917 frequently. Also note that some servers enforce a delay of a
918 few seconds after each quit, so fetchmail may not be able to get
919 back in immediately after an expunge -- you may see "lock busy"
920 errors if this happens. If you specify this option to an integer
921 N, it tells fetchmail to only issue expunges on every Nth
922 delete. An argument of zero suppresses expunges entirely (so no
923 expunges at all will be done until the end of run). This option
924 does not work with ETRN or ODMR.
925 Authentication Options
928 -u <name> | --user <name> | --username <name>
929 (Keyword: user[name])
930 Specifies the user identification to be used when logging in to
931 the mail server. The appropriate user identification is both
932 server and user-dependent. The default is your login name on
933 the client machine that is running fetchmail. See USER AUTHEN‐
934 TICATION below for a complete description.
935 -I <specification> | --interface <specification>
937 (Keyword: interface)
938 Require that a specific interface device be up and have a spe‐
939 cific local or remote IPv4 (IPv6 is not supported by this option
940 yet) address (or range) before polling. Frequently fetchmail is
941 used over a transient point-to-point TCP/IP link established di‐
942 rectly to a mail server via SLIP or PPP. That is a relatively
943 secure channel. But when other TCP/IP routes to the mail server
944 exist (e.g., when the link is connected to an alternate ISP),
945 your username and password may be vulnerable to snooping (espe‐
946 cially when daemon mode automatically polls for mail, shipping a
947 clear password over the net at predictable intervals). The
948 --interface option may be used to prevent this. When the speci‐
949 fied link is not up or is not connected to a matching IP ad‐
950 dress, polling will be skipped. The format is:
951 interface/iii.iii.iii.iii[/mmm.mmm.mmm.mmm]
953 The field before the first slash is the interface name (i.e.,
955 sl0, ppp0 etc.). The field before the second slash is the ac‐
956 ceptable IP address. The field after the second slash is a mask
957 which specifies a range of IP addresses to accept. If no mask
958 is present 255.255.255.255 is assumed (i.e., an exact match).
959 This option is currently only supported under Linux and FreeBSD.
960 Please see the monitor section for below for FreeBSD specific
961 information.
962 Note that this option may be removed from a future fetchmail
964 version.
965 -M <interface> | --monitor <interface>
967 (Keyword: monitor)
968 Daemon mode can cause transient links which are automatically
969 taken down after a period of inactivity (e.g., PPP links) to re‐
970 main up indefinitely. This option identifies a system TCP/IP
971 interface to be monitored for activity. After each poll inter‐
972 val, if the link is up but no other activity has occurred on the
973 link, then the poll will be skipped. However, when fetchmail is
974 woken up by a signal, the monitor check is skipped and the poll
975 goes through unconditionally. This option is currently only
976 supported under Linux and FreeBSD. For the monitor and inter‐
977 face options to work for non root users under FreeBSD, the
978 fetchmail binary must be installed setgid kmem. This would be a
979 security hole, but fetchmail runs with the effective GID set to
980 that of the kmem group only when interface data is being col‐
981 lected.
982 Note that this option may be removed from a future fetchmail
984 version.
985 --auth <type>
987 (Keyword: auth[enticate])
988 This option permits you to specify an authentication type (see
989 USER AUTHENTICATION below for details). The possible values are
990 any, password, kerberos_v5, kerberos (or, for excruciating ex‐
991 actness, kerberos_v4), gssapi, cram-md5, otp, ntlm, msn (only
992 for POP3), external (only IMAP) and ssh. When any (the default)
993 is specified, fetchmail tries first methods that do not require
994 a password (EXTERNAL, GSSAPI, KERBEROS IV, KERBEROS 5); then it
995 looks for methods that mask your password (CRAM-MD5, NTLM, X-OTP
996 - note that MSN is only supported for POP3, but not auto-
997 probed); and only if the server does not support any of those
998 will it ship your password unencrypted. Other values may be
999 used to force various authentication methods: ssh suppresses au‐
1000 thentication and is thus useful for IMAP PREAUTH (if you are us‐
1001 ing a secure --plugin, for instance, a properly configured ssh,
1002 you may also need to set --sslproto '' or, in the rcfile, ssl‐
1003 proto '', in order to avoid fetchmail negotiating STARTTLS over
1004 SSH). external suppresses authentication and is thus useful for
1005 IMAP EXTERNAL. Any value other than password, cram-md5, ntlm,
1006 msn or otp suppresses fetchmail's normal inquiry for a password.
1007 Specify ssh when you are using an end-to-end secure connection
1008 such as an ssh tunnel (in this case you may also want to specify
1009 --sslproto '', which see); specify external when you use TLS
1010 with client authentication and specify gssapi or kerberos_v4 if
1011 you are using a protocol variant that employs GSSAPI or K4.
1012 Choosing KPOP protocol automatically selects Kerberos authenti‐
1013 cation. This option does not work with ETRN. GSSAPI service
1014 names are in line with RFC-2743 and IANA registrations, see
1015 Generic Security Service Application Program Interface
1016 (GSSAPI)/Kerberos/Simple Authentication and Security Layer
1017 (SASL) Service Names ⟨https://www.iana.org/assignments/gssapi-
1018 service-names/⟩.
1019 Miscellaneous Options
1021 -f <pathname> | --fetchmailrc <pathname>
1022 Specify a non-default name for the ~/.fetchmailrc run control
1023 file. The pathname argument must be either "-" (a single dash,
1024 meaning to read the configuration from standard input) or a
1025 filename. Unless the --version option is also on, a named file
1026 argument must have permissions no more open than 0700
1027 (u=rwx,g=,o=) or else be /dev/null.
1028 -i <pathname> | --idfile <pathname>
1030 (Keyword: idfile)
1031 Specify an alternate name for the .fetchids file used to save
1032 message UIDs. NOTE: since fetchmail 6.3.0, write access to the
1033 directory containing the idfile is required, as fetchmail writes
1034 a temporary file and renames it into the place of the real id‐
1035 file only if the temporary file has been written successfully.
1036 This avoids the truncation of idfiles when running out of disk
1037 space.
1038 --pidfile <pathname>
1040 (Keyword: pidfile; since fetchmail v6.3.4)
1041 Override the default location of the PID file that is used as a
1042 lock file. Default: see "ENVIRONMENT" below. Note that many
1043 places in the code and documentation, the term "lock file" is
1044 used. This file contains the process ID of the running fetch‐
1045 mail on the first line and potentially the daemon interval on a
1046 second line.
1047 -n | --norewrite
1049 (Keyword: no rewrite)
1050 Normally, fetchmail edits RFC-822 address headers (To, From, Cc,
1051 Bcc, and Reply-To) in fetched mail so that any mail IDs local to
1052 the server are expanded to full addresses (@ and the mail server
1053 host name are appended). This enables replies on the client to
1054 get addressed correctly (otherwise your mailer might think they
1055 should be addressed to local users on the client machine!).
1056 This option disables the rewrite. (This option is provided to
1057 pacify people who are paranoid about having an MTA edit mail
1058 headers and want to know they can prevent it, but it is gener‐
1059 ally not a good idea to actually turn off rewrite.) When using
1060 ETRN or ODMR, the rewrite option is ineffective.
1061 -E <line> | --envelope <line>
1063 (Keyword: envelope; Multidrop only)
1064 In the configuration file, an enhanced syntax is used:
1065 envelope [<count>] <line>
1066 This option changes the header fetchmail assumes will carry a
1068 copy of the mail's envelope address. Normally this is 'X-Enve‐
1069 lope-To'. Other typically found headers to carry envelope in‐
1070 formation are 'X-Original-To' and 'Delivered-To'. Now, since
1071 these headers are not standardized, practice varies. See the
1072 discussion of multidrop address handling below. As a special
1073 case, 'envelope "Received"' enables parsing of sendmail-style
1074 Received lines. This is the default, but discouraged because it
1075 is not fully reliable.
1076 Note that fetchmail expects the Received-line to be in a spe‐
1078 cific format: It must contain "by host for address", where host
1079 must match one of the mail server names that fetchmail recog‐
1080 nizes for the account in question.
1081 The optional count argument (only available in the configuration
1083 file) determines how many header lines of this kind are skipped.
1084 A count of 1 means: skip the first, take the second. A count of
1085 2 means: skip the first and second, take the third, and so on.
1086 -Q <prefix> | --qvirtual <prefix>
1088 (Keyword: qvirtual; Multidrop only)
1089 The string prefix assigned to this option will be removed from
1090 the user name found in the header specified with the envelope
1091 option (before doing multidrop name mapping or localdomain
1092 checking, if either is applicable). This option is useful if you
1093 are using fetchmail to collect the mail for an entire domain and
1094 your ISP (or your mail redirection provider) is using qmail.
1095 One of the basic features of qmail is the Delivered-To: message
1096 header. Whenever qmail delivers a message to a local mailbox it
1097 puts the username and host name of the envelope recipient on
1098 this line. The major reason for this is to prevent mail loops.
1099 To set up qmail to batch mail for a disconnected site the ISP-
1100 mailhost will have normally put that site in its 'Virtualhosts'
1101 control file so it will add a prefix to all mail addresses for
1102 this site. This results in mail sent to 'username@userhost.user‐
1103 dom.dom.com' having a Delivered-To: line of the form:
1104 Delivered-To: mbox-userstr-username@userhost.example.com
1106 The ISP can make the 'mbox-userstr-' prefix anything they choose
1108 but a string matching the user host name is likely. By using
1109 the option 'envelope Delivered-To:' you can make fetchmail reli‐
1110 ably identify the original envelope recipient, but you have to
1111 strip the 'mbox-userstr-' prefix to deliver to the correct user.
1112 This is what this option is for.
1113 --configdump
1115 Parse the ~/.fetchmailrc file, interpret any command-line op‐
1116 tions specified, and dump a configuration report to standard
1117 output. The configuration report is a data structure assignment
1118 in the language Python. This option is meant to be used with an
1119 interactive ~/.fetchmailrc editor like fetchmailconf, written in
1120 Python.
1121 -y | --yydebug
1123 Enables parser debugging, this option is meant to be used by de‐
1124 velopers only.
1125 Removed Options
1128 -T | --netsec
1129 Removed before version 6.3.0, the required underlying inet6_apps
1130 library had been discontinued and is no longer available.
1131
1134 All modes except ETRN require authentication of the client to the
1135 server. Normal user authentication in fetchmail is very much like the
1136 authentication mechanism of ftp(1). The correct user-id and password
1137 depend upon the underlying security system at the mail server.
1138 If the mail server is a Unix machine on which you have an ordinary user
1140 account, your regular login name and password are used with fetchmail.
1141 If you use the same login name on both the server and the client ma‐
1142 chines, you needn't worry about specifying a user-id with the -u option
1143 -- the default behavior is to use your login name on the client machine
1144 as the user-id on the server machine. If you use a different login
1145 name on the server machine, specify that login name with the -u option.
1146 E.g., if your login name is 'jsmith' on a machine named 'mailgrunt',
1147 you would start fetchmail as follows:
1148 fetchmail -u jsmith mailgrunt
1150 The default behavior of fetchmail is to prompt you for your mail server
1152 password before the connection is established. This is the safest way
1153 to use fetchmail and ensures that your password will not be compro‐
1154 mised. You may also specify your password in your ~/.fetchmailrc file.
1155 This is convenient when using fetchmail in daemon mode or with scripts.
1156 Using netrc files
1159 If you do not specify a password, and fetchmail cannot extract one from
1160 your ~/.fetchmailrc file, it will look for a ~/.netrc file in your home
1161 directory before requesting one interactively; if an entry matching the
1162 mail server is found in that file, the password will be used. Fetch‐
1163 mail first looks for a match on poll name; if it finds none, it checks
1164 for a match on via name. See the ftp(1) man page for details of the
1165 syntax of the ~/.netrc file. To show a practical example, a .netrc
1166 might look like this:
1167 machine hermes.example.org
1169 login joe
1170 password topsecret
1171 You can repeat this block with different user information if you need
1173 to provide more than one password.
1174 This feature may allow you to avoid duplicating password information in
1176 more than one file.
1177 On mail servers that do not provide ordinary user accounts, your user-
1179 id and password are usually assigned by the server administrator when
1180 you apply for a mailbox on the server. Contact your server administra‐
1181 tor if you do not know the correct user-id and password for your mail‐
1182 box account.
1183 Secure Socket Layers (SSL) and Transport Layer Security (TLS)
1186 All retrieval protocols can use SSL or TLS wrapping for the transport.
1187 Additionally, POP3 and IMAP retrieval can also negotiate SSL/TLS by
1188 means of STARTTLS (or STLS).
1189 You can access TLS-encrypted services by specifying the options start‐
1191 ing with --ssl, such as --ssl, --sslproto, --sslcertck, and others.
1192 You can also do this using the corresponding user options in the
1193 .fetchmailrc file. Some services, such as POP3 and IMAP, have differ‐
1194 ent well known ports defined for the SSL encrypted services. The en‐
1195 crypted ports will be selected automatically when SSL is enabled and no
1196 explicit port is specified. Also, the --sslcertck command line or
1197 sslcertck run control file option should be used to force strict cer‐
1198 tificate checking with older fetchmail versions - see below.
1199 If TLS or SSL is not configured, fetchmail will usually still try to
1201 use STARTTLS somewhat opportunistically. In practice, is it still
1202 mandatory because --sslcertck is a default setting and implicitly re‐
1203 quires STARTTLS.
1204 STARTTLS can be enforced by using --sslproto auto and defeated by using
1206 --sslproto ''. STARTTLS connections use the same port as the unen‐
1207 crypted version of the protocol and negotiate TLS via special command.
1208 The --sslcertck command line or sslcertck run control file option
1209 should be used to force strict certificate checking - see below.
1210 --sslcertck is recommended: When connecting to an SSL or TLS encrypted
1212 server, the server presents a certificate to the client for validation.
1213 The certificate is checked to verify that the common name in the cer‐
1214 tificate matches the name of the server being contacted and that the
1215 effective and expiration dates in the certificate indicate that it is
1216 currently valid. If any of these checks fail, a warning message is
1217 printed, but the connection continues. The server certificate does not
1218 need to be signed by any specific Certifying Authority and may be a
1219 "self-signed" certificate. If the --sslcertck command line option or
1220 sslcertck run control file option is used, fetchmail will instead abort
1221 if any of these checks fail, because it must assume that there is a
1222 man-in-the-middle attack in this scenario, hence fetchmail must not ex‐
1223 pose clear-text passwords. Use of the sslcertck or --sslcertck option
1224 is therefore advised; it has become the default in fetchmail 6.4.0.
1225 Some SSL encrypted servers may request a client side certificate. A
1227 client side public SSL certificate and private SSL key may be speci‐
1228 fied. If requested by the server, the client certificate is sent to
1229 the server for validation. Some servers may require a valid client
1230 certificate and may refuse connections if a certificate is not provided
1231 or if the certificate is not valid. Some servers may require client
1232 side certificates be signed by a recognized Certifying Authority. The
1233 format for the key files and the certificate files is that required by
1234 the underlying SSL libraries (OpenSSL in the general case).
1235 A word of care about the use of SSL: While above mentioned setup with
1237 self-signed server certificates retrieved over the wires can protect
1238 you from a passive eavesdropper, it does not help against an active at‐
1239 tacker. It is clearly an improvement over sending the passwords in
1240 clear, but you should be aware that a man-in-the-middle attack is triv‐
1241 ially possible (in particular with tools such as dsniff
1242 ⟨https://monkey.org/~dugsong/dsniff/⟩). Use of strict certificate
1243 checking with a certification authority recognized by server and
1244 client, or perhaps of an SSH tunnel (see below for some examples) is
1245 preferable if you care seriously about the security of your mailbox and
1246 passwords.
1247
1250 Early versions of POP3 (RFC1081, RFC1225) supported a crude form of in‐
1251 dependent authentication using the .rhosts file on the mail server
1252 side. Under this RPOP variant, a fixed per-user ID equivalent to a
1253 password was sent in clear over a link to a reserved port, with the
1254 command RPOP rather than PASS to alert the server that it should do
1255 special checking. RPOP is supported by fetchmail (you can specify
1256 'protocol RPOP' to have the program send 'RPOP' rather than 'PASS') but
1257 its use is strongly discouraged, and support will be removed from a fu‐
1258 ture fetchmail version. This facility was vulnerable to spoofing and
1259 was withdrawn in RFC1460.
1260 RFC1460 introduced APOP authentication. In this variant of POP3, you
1262 register an APOP password on your server host (on some servers, the
1263 program to do this is called popauth(8)). You put the same password in
1264 your ~/.fetchmailrc file. Each time fetchmail logs in, it sends an MD5
1265 hash of your password and the server greeting time to the server, which
1266 can verify it by checking its authorization database.
1267 Note that APOP is no longer considered resistant against man-in-the-
1269 middle attacks.
1270 RETR or TOP
1273 fetchmail makes some efforts to make the server believe messages had
1274 not been retrieved, by using the TOP command with a large number of
1275 lines when possible. TOP is a command that retrieves the full header
1276 and a fetchmail-specified amount of body lines. It is optional and
1277 therefore not implemented by all servers, and some are known to imple‐
1278 ment it improperly. On many servers however, the RETR command which re‐
1279 trieves the full message with header and body, sets the "seen" flag
1280 (for instance, in a web interface), whereas the TOP command does not do
1281 that.
1282 fetchmail will always use the RETR command if "fetchall" is set.
1284 fetchmail will also use the RETR command if "keep" is set and "uidl" is
1285 unset. Finally, fetchmail will use the RETR command on Maillennium
1286 POP3/PROXY servers (used by Comcast) to avoid a deliberate TOP misin‐
1287 terpretation in this server that causes message corruption.
1288 In all other cases, fetchmail will use the TOP command. This implies
1290 that in "keep" setups, "uidl" must be set if "TOP" is desired.
1291 Note that this description is true for the current version of fetch‐
1293 mail, but the behavior may change in future versions. In particular,
1294 fetchmail may prefer the RETR command because the TOP command causes
1295 much grief on some servers and is only optional.
1296
1298 If your fetchmail was built with Kerberos support and you specify Ker‐
1299 beros authentication (either with --auth or the .fetchmailrc option au‐
1300 thenticate kerberos_v4) it will try to get a Kerberos ticket from the
1301 mail server at the start of each query. Note: if either the pollname
1302 or via name is 'hesiod', fetchmail will try to use Hesiod to look up
1303 the mail server.
1304 If you use POP3 or IMAP with GSSAPI authentication, fetchmail will ex‐
1306 pect the server to have RFC1731- or RFC1734-conforming GSSAPI capabil‐
1307 ity, and will use it. Currently this has only been tested over Ker‐
1308 beros 5, so you are expected to already have a ticket-granting ticket.
1309 You may pass a username different from your principal name using the
1310 standard --user command or by the .fetchmailrc option user.
1311 If your IMAP daemon returns the PREAUTH response in its greeting line,
1313 fetchmail will notice this and skip the normal authentication step.
1314 This can be useful, e.g., if you start imapd explicitly using ssh. In
1315 this case you can declare the authentication value 'ssh' on that site
1316 entry to stop .fetchmail from asking you for a password when it starts
1317 up.
1318 If you use client authentication with TLS1 and your IMAP daemon returns
1320 the AUTH=EXTERNAL response, fetchmail will notice this and will use the
1321 authentication shortcut and will not send the passphrase. In this case
1322 you can declare the authentication value 'external'
1323 on that site to stop fetchmail from asking you for a password when it
1324 starts up.
1325 If you are using POP3, and the server issues a one-time-password chal‐
1327 lenge conforming to RFC1938, fetchmail will use your password as a pass
1328 phrase to generate the required response. This avoids sending secrets
1329 over the net unencrypted.
1330 Compuserve's RPA authentication is supported. If you compile in the
1332 support, fetchmail will try to perform an RPA pass-phrase authentica‐
1333 tion instead of sending over the password unencrypted if it detects
1334 "@compuserve.com" in the host name.
1335 If you are using IMAP, Microsoft's NTLM authentication (used by Micro‐
1337 soft Exchange) is supported. If you compile in the support, fetchmail
1338 will try to perform an NTLM authentication (instead of sending over the
1339 password unencrypted) whenever the server returns AUTH=NTLM in its ca‐
1340 pability response. Specify a user option value that looks like
1341 'user@domain': the part to the left of the @ will be passed as the
1342 username and the part to the right as the NTLM domain.
1343 ESMTP AUTH
1346 fetchmail also supports authentication to the ESMTP server on the
1347 client side according to RFC 2554. You can specify a name/password
1348 pair to be used with the keywords 'esmtpname' and 'esmtppassword'; the
1349 former defaults to the username of the calling user.
1350
1353 Introducing the daemon mode
1354 In daemon mode, fetchmail puts itself into the background and runs for‐
1355 ever, querying each specified host and then sleeping for a given
1356 polling interval.
1357 Starting the daemon mode
1359 There are several ways to make fetchmail work in daemon mode. On the
1360 command line, --daemon <interval> or -d <interval> option runs fetch‐
1361 mail in daemon mode. You must specify a numeric argument which is a
1362 polling interval (time to wait after completing a whole poll cycle with
1363 the last server and before starting the next poll cycle with the first
1364 server) in seconds.
1365 Example: simply invoking
1367 fetchmail -d 900
1369 will, therefore, poll all the hosts described in your ~/.fetchmailrc
1371 file (except those explicitly excluded with the 'skip' verb) a bit less
1372 often than once every 15 minutes (exactly: 15 minutes + time that the
1373 poll takes).
1374 It is also possible to set a polling interval in your ~/.fetchmailrc
1376 file by saying 'set daemon <interval>', where <interval> is an integer
1377 number of seconds. If you do this, fetchmail will always start in dae‐
1378 mon mode unless you override it with the command-line option --daemon 0
1379 or -d0.
1380 Only one daemon process is permitted per user; in daemon mode, fetch‐
1382 mail sets up a per-user lock file to guarantee this. (You can however
1383 cheat and set the FETCHMAILHOME environment variable to overcome this
1384 setting, but in that case, it is your responsibility to make sure you
1385 are not polling the same server with two processes at the same time.)
1386 Awakening the background daemon
1388 Normally, calling fetchmail with a daemon in the background sends a
1389 wake-up signal to the daemon and quits without output. The background
1390 daemon then starts its next poll cycle immediately. The wake-up sig‐
1391 nal, SIGUSR1, can also be sent manually. The wake-up action also clears
1392 any 'wedged' flags indicating that connections have wedged due to
1393 failed authentication or multiple timeouts.
1394 Terminating the background daemon
1396 The option -q or --quit will kill a running daemon process instead of
1397 waking it up (if there is no such process, fetchmail will notify you).
1398 If the --quit option appears last on the command line, fetchmail will
1399 kill the running daemon process and then quit. Otherwise, fetchmail
1400 will first kill a running daemon process and then continue running with
1401 the other options.
1402 Useful options for daemon mode
1404 The -L <filename> or --logfile <filename> option (keyword: set logfile)
1405 is only effective when fetchmail is detached and in daemon mode. Note
1406 that the logfile must exist before fetchmail is run, you can use the
1407 touch(1) command with the filename as its sole argument to create it.
1408 This option allows you to redirect status messages into a specified
1409 logfile (follow the option with the logfile name). The logfile is
1410 opened for append, so previous messages are not deleted. This is pri‐
1411 marily useful for debugging configurations. Note that fetchmail does
1412 not detect if the logfile is rotated, the logfile is only opened once
1413 when fetchmail starts. You need to restart fetchmail after rotating the
1414 logfile and before compressing it (if applicable).
1415 The --syslog option (keyword: set syslog) allows you to redirect status
1417 and error messages emitted to the syslog(3) system daemon if available.
1418 Messages are logged with an id of fetchmail, the facility LOG_MAIL, and
1419 priorities LOG_ERR, LOG_ALERT or LOG_INFO. This option is intended for
1420 logging status and error messages which indicate the status of the dae‐
1421 mon and the results while fetching mail from the server(s). Error mes‐
1422 sages for command line options and parsing the .fetchmailrc file are
1423 still written to stderr, or to the specified log file. The --nosyslog
1424 option turns off use of syslog(3), assuming it is turned on in the
1425 ~/.fetchmailrc file. This option is overridden, in certain situations,
1426 by --logfile (which see).
1427 The -N or --nodetach option suppresses backgrounding and detachment of
1429 the daemon process from its control terminal. This is useful for de‐
1430 bugging or when fetchmail runs as the child of a supervisor process
1431 such as init(8) or Gerrit Pape's runit(8). Note that this also causes
1432 the logfile option to be ignored.
1433 Note that while running in daemon mode polling a POP2 or IMAP2bis
1435 server, transient errors (such as DNS failures or sendmail delivery re‐
1436 fusals) may force the fetchall option on for the duration of the next
1437 polling cycle. This is a robustness feature. It means that if a mes‐
1438 sage is fetched (and thus marked seen by the mail server) but not de‐
1439 livered locally due to some transient error, it will be re-fetched dur‐
1440 ing the next poll cycle. (The IMAP logic does not delete messages un‐
1441 til they are delivered, so this problem does not arise.)
1442 If you touch or change the ~/.fetchmailrc file while fetchmail is run‐
1444 ning in daemon mode, this will be detected at the beginning of the next
1445 poll cycle. When a changed ~/.fetchmailrc is detected, fetchmail
1446 rereads it and restarts from scratch (using exec(2); no state informa‐
1447 tion is retained in the new instance). Note that if fetchmail needs to
1448 query for passwords, of that if you break the ~/.fetchmailrc file's
1449 syntax, the new instance will softly and silently vanish away on
1450 startup.
1451
1454 The --postmaster <name> option (keyword: set postmaster) specifies the
1455 last-resort username to which multidrop mail is to be forwarded if no
1456 matching local recipient can be found. It is also used as destination
1457 of undeliverable mail if the 'bouncemail' global option is off and ad‐
1458 ditionally for spam-blocked mail if the 'bouncemail' global option is
1459 off and the 'spambounce' global option is on. This option defaults to
1460 the user who invoked fetchmail. If the invoking user is root, then the
1461 default of this option is the user 'postmaster'. Setting postmaster to
1462 the empty string causes such mail as described above to be discarded -
1463 this however is usually a bad idea. See also the description of the
1464 'FETCHMAILUSER' environment variable in the ENVIRONMENT section below.
1465 The --nobounce behaves like the "set no bouncemail" global option,
1467 which see.
1468 The --invisible option (keyword: set invisible) tries to make fetchmail
1470 invisible. Normally, fetchmail behaves like any other MTA would -- it
1471 generates a Received header into each message describing its place in
1472 the chain of transmission, and tells the MTA it forwards to that the
1473 mail came from the machine fetchmail itself is running on. If the in‐
1474 visible option is on, the Received header is suppressed and fetchmail
1475 tries to spoof the MTA it forwards to into thinking it came directly
1476 from the mail server host.
1477 The --showdots option (keyword: set showdots) forces fetchmail to show
1479 progress dots even if the output goes to a file or fetchmail is not in
1480 verbose mode. Fetchmail shows the dots by default when run in --ver‐
1481 bose mode and output goes to console. This option is ignored in
1482 --silent mode.
1483 By specifying the --tracepolls option, you can ask fetchmail to add in‐
1485 formation to the Received header on the form "polling {label} account
1486 {user}", where {label} is the account label (from the specified rcfile,
1487 normally ~/.fetchmailrc) and {user} is the username which is used to
1488 log on to the mail server. This header can be used to make filtering
1489 email where no useful header information is available and you want mail
1490 from different accounts sorted into different mailboxes (this could,
1491 for example, occur if you have an account on the same server running a
1492 mailing list, and are subscribed to the list using that account). The
1493 default is not adding any such header. In .fetchmailrc, this is called
1494 'tracepolls'.
1495
1498 The protocols fetchmail uses to talk to mail servers are next to bul‐
1499 letproof. In normal operation forwarding to port 25, no message is
1500 ever deleted (or even marked for deletion) on the host until the SMTP
1501 listener on the client side has acknowledged to fetchmail that the mes‐
1502 sage has been either accepted for delivery or rejected due to a spam
1503 block.
1504 When forwarding to an MDA, however, there is more possibility of error.
1506 Some MDAs are 'safe' and reliably return a nonzero status on any deliv‐
1507 ery error, even one due to temporary resource limits. The maildrop(1)
1508 program is like this; so are most programs designed as mail transport
1509 agents, such as sendmail(1), including the sendmail wrapper of Postfix
1510 and exim(1). These programs give back a reliable positive acknowledge‐
1511 ment and can be used with the mda option with no risk of mail loss.
1512 Unsafe MDAs, though, may return 0 even on delivery failure. If this
1513 happens, you will lose mail.
1514 The normal mode of fetchmail is to try to download only 'new' messages,
1516 leaving untouched (and undeleted) messages you have already read di‐
1517 rectly on the server (or fetched with a previous fetchmail --keep).
1518 But you may find that messages you have already read on the server are
1519 being fetched (and deleted) even when you do not specify --all. There
1520 are several reasons this can happen.
1521 One could be that you are using POP2. The POP2 protocol includes no
1523 representation of 'new' or 'old' state in messages, so fetchmail must
1524 treat all messages as new all the time. But POP2 is obsolete, so this
1525 is unlikely.
1526 A potential POP3 problem might be servers that insert messages in the
1528 middle of mailboxes (some VMS implementations of mail are rumored to do
1529 this). The fetchmail code assumes that new messages are appended to
1530 the end of the mailbox; when this is not true it may treat some old
1531 messages as new and vice versa. Using UIDL whilst setting fastuidl 0
1532 might fix this, otherwise, consider switching to IMAP.
1533 Yet another POP3 problem is that if they cannot make temporary files in
1535 the user's home directory, some POP3 servers will hand back an undocu‐
1536 mented response that causes fetchmail to spuriously report "No mail".
1537 The IMAP code uses the presence or absence of the server flag \Seen to
1539 decide whether or not a message is new. This is not the right thing to
1540 do, fetchmail should check the UIDVALIDITY and use UID, but it does not
1541 do that yet. Under Unix, it counts on your IMAP server to notice the
1542 BSD-style Status flags set by mail user agents and set the \Seen flag
1543 from them when appropriate. All Unix IMAP servers we know of do this,
1544 though it is not specified by the IMAP RFCs. If you ever trip over a
1545 server that does not, the symptom will be that messages you have al‐
1546 ready read on your host will look new to the server. In this (un‐
1547 likely) case, only messages you fetched with fetchmail --keep will be
1548 both undeleted and marked old.
1549 In ETRN and ODMR modes, fetchmail does not actually retrieve messages;
1551 instead, it asks the server's SMTP listener to start a queue flush to
1552 the client via SMTP. Therefore it sends only undelivered messages.
1553
1556 Many SMTP listeners allow administrators to set up 'spam filters' that
1557 block unsolicited email from specified domains. A MAIL FROM or DATA
1558 line that triggers this feature will elicit an SMTP response which (un‐
1559 fortunately) varies according to the listener.
1560 Newer versions of sendmail return an error code of 571.
1562 According to RFC2821, the correct thing to return in this situation is
1564 550 "Requested action not taken: mailbox unavailable" (the draft adds
1565 "[E.g., mailbox not found, no access, or command rejected for policy
1566 reasons].").
1567 Older versions of the exim MTA return 501 "Syntax error in parameters
1569 or arguments".
1570 The postfix MTA runs 554 as an antispam response.
1572 Zmailer may reject code with a 500 response (followed by an enhanced
1574 status code that contains more information).
1575 Return codes which fetchmail treats as antispam responses and discards
1577 the message can be set with the 'antispam' option. This is one of the
1578 only three circumstance under which fetchmail ever discards mail (the
1579 others are the 552 and 553 errors described below, and the suppression
1580 of multi-dropped messages with a message-ID already seen).
1581 If fetchmail is fetching from an IMAP server, the antispam response
1583 will be detected and the message rejected immediately after the headers
1584 have been fetched, without reading the message body. Thus, you will
1585 not pay for downloading spam message bodies.
1586 By default, the list of antispam responses is empty.
1588 If the spambounce global option is on, mail that is spam-blocked trig‐
1590 gers an RFC1892/RFC1894 bounce message informing the originator that we
1591 do not accept mail from it. See also BUGS.
1592
1595 Besides the spam-blocking described above, fetchmail takes special ac‐
1596 tions — that may be modified by the --softbounce option — on the fol‐
1597 lowing SMTP/ESMTP error response codes
1598 452 (insufficient system storage)
1600 Leave the message in the server mailbox for later retrieval.
1601 552 (message exceeds fixed maximum message size)
1603 Delete the message from the server. Send bounce-mail to the orig‐
1604 inator.
1605 553 (invalid sending domain)
1607 Delete the message from the server. Do not even try to send
1608 bounce-mail to the originator.
1609 Other errors greater or equal to 500 trigger bounce mail back to the
1611 originator, unless suppressed by --softbounce. See also BUGS.
1612
1615 The preferred way to set up fetchmail is to write a .fetchmailrc file
1616 in your home directory (you may do this directly, with a text editor,
1617 or indirectly via fetchmailconf). When there is a conflict between the
1618 command-line arguments and the arguments in this file, the command-line
1619 arguments take precedence.
1620 To protect the security of your passwords, your ~/.fetchmailrc may not
1622 normally have more than 0700 (u=rwx,g=,o=) permissions; fetchmail will
1623 complain and exit otherwise (this check is suppressed when --version is
1624 on).
1625 You may read the .fetchmailrc file as a list of commands to be executed
1627 when fetchmail is called with no arguments.
1628 Run Control Syntax
1630 Comments begin with a '#' and extend through the end of the line. Oth‐
1631 erwise the file consists of a series of server entries or global option
1632 statements in a free-format, token-oriented syntax.
1633 There are four kinds of tokens: grammar keywords, numbers (i.e., deci‐
1635 mal digit sequences), unquoted strings, and quoted strings. A quoted
1636 string is bounded by double quotes and may contain whitespace (and
1637 quoted digits are treated as a string). Note that quoted strings will
1638 also contain line feed characters if they run across two or more lines,
1639 unless you use a backslash to join lines (see below). An unquoted
1640 string is any whitespace-delimited token that is neither numeric,
1641 string quoted nor contains the special characters ',', ';', ':', or
1642 '='.
1643 Any amount of whitespace separates tokens in server entries, but is
1645 otherwise ignored. You may use backslash escape sequences (\n for LF,
1646 \t for HT, \b for BS, \r for CR, \nnn for decimal (where nnn cannot
1647 start with a 0), \0ooo for octal, and \xhh for hex) to embed non-print‐
1648 able characters or string delimiters in strings. In quoted strings, a
1649 backslash at the very end of a line will cause the backslash itself and
1650 the line feed (LF or NL, new line) character to be ignored, so that you
1651 can wrap long strings. Without the backslash at the line end, the line
1652 feed character would become part of the string.
1653 Warning: while these resemble C-style escape sequences, they are not
1655 the same. fetchmail only supports these eight styles. C supports more
1656 escape sequences that consist of backslash (\) and a single character,
1657 but does not support decimal codes and does not require the leading 0
1658 in octal notation. Example: fetchmail interprets \233 the same as \xE9
1659 (Latin small letter e with acute), where C would interpret \233 as oc‐
1660 tal 0233 = \x9B (CSI, control sequence introducer).
1661 Each server entry consists of one of the keywords 'poll' or 'skip',
1663 followed by a server name, followed by server options, followed by any
1664 number of user (or username) descriptions, followed by user options.
1665 Note: the most common cause of syntax errors is mixing up user and
1666 server options or putting user options before the user descriptions.
1667 For backward compatibility, the word 'server' is a synonym for 'poll'.
1669 You can use the noise keywords 'and', 'with', 'has', 'wants', and 'op‐
1671 tions' anywhere in an entry to make it resemble English. They are ig‐
1672 nored, but can make entries much easier to read at a glance. The punc‐
1673 tuation characters ':', ';' and ',' are also ignored.
1674 Poll versus Skip
1676 The 'poll' verb tells fetchmail to query this host when it is run with
1677 no arguments. The 'skip' verb tells fetchmail not to poll this host
1678 unless it is explicitly named on the command line. (The 'skip' verb
1679 allows you to experiment with test entries safely, or easily disable
1680 entries for hosts that are temporarily down.)
1681
1684 Here are the legal options. Keyword suffixes enclosed in square brack‐
1685 ets are optional. Those corresponding to short command-line options
1686 are followed by '-' and the appropriate option letter. If option is
1687 only relevant to a single mode of operation, it is noted as 's' or 'm'
1688 for singledrop- or multidrop-mode, respectively.
1689 Here are the legal global options:
1691 Keyword Opt Mode Function
1694 ────────────────────────────────────────────────────────────────────
1695 set daemon -d Set a background poll interval in
1696 seconds.
1697 set postmaster Give the name of the last-resort
1698 mail recipient (default: user run‐
1699 ning fetchmail, "postmaster" if
1700 run by the root user)
1701 set bouncemail Direct error mail to the sender
1702 (default)
1703 set no bouncemail Direct error mail to the local
1704 postmaster (as per the 'postmas‐
1705 ter' global option above).
1706 set no spambounce Do not bounce spam-blocked mail
1707 (default).
1708 set spambounce Bounce blocked spam-blocked mail
1709 (as per the 'antispam' user op‐
1710 tion) back to the destination as
1711 indicated by the 'bouncemail'
1712 global option. Warning: Do not
1713 use this to bounce spam back to
1714 the sender - most spam is sent
1715 with false sender address and thus
1716 this option hurts innocent by‐
1717 standers.
1718 set no softbounce Delete permanently undeliverable
1719 mail. It is recommended to use
1720 this option if the configuration
1721 has been thoroughly tested.
1722 set softbounce Keep permanently undeliverable
1726 mail as though a temporary error
1727 had occurred (default).
1728 set logfile -L Name of a file to append error and
1729 status messages to. Only effec‐
1730 tive in daemon mode and if fetch‐
1731 mail detaches. If effective,
1732 overrides set syslog.
1733 set pidfile -p Name of the PID file.
1734 set idfile -i Name of the file to store UID
1735 lists in.
1736 set syslog Do error logging through sys‐
1737 log(3). May be overridden by set
1738 logfile.
1739 set no syslog Turn off error logging through
1740 syslog(3). (default)
1741 set properties String value that is ignored by
1742 fetchmail (may be used by exten‐
1743 sion scripts).
1744 Here are the legal server options:
1746 Keyword Opt Mode Function
1749 ─────────────────────────────────────────────────────────────────
1750 via Specify DNS name of mail server,
1751 overriding poll name
1752 proto[col] -p Specify protocol (case insensi‐
1753 tive): POP2, POP3, IMAP, APOP,
1754 KPOP
1755 local[domains] m Specify domain(s) to be regarded
1756 as local
1757 port Specify TCP/IP service port (obso‐
1758 lete, use 'service' instead).
1759 service -P Specify service name (a numeric
1760 value is also allowed and consid‐
1761 ered a TCP/IP port number).
1762 auth[enticate] Set authentication type (default
1763 'any')
1764 timeout -t Server inactivity timeout in sec‐
1765 onds (default 300)
1766 envelope -E m Specify envelope-address header
1767 name
1768 no envelope m Disable looking for envelope ad‐
1769 dress
1770 qvirtual -Q m Qmail virtual domain prefix to re‐
1771 move from user name
1772 aka m Specify alternate DNS names of
1773 mail server
1774 interface -I specify IP interface(s) that must
1775 be up for server poll to take
1776 place
1777 monitor -M Specify IP address to monitor for
1778 activity
1779 plugin Specify command through which to
1780 make server connections.
1781 plugout Specify command through which to
1782 make listener connections.
1783 dns m Enable DNS lookup for multidrop
1784 (default)
1785 no dns m Disable DNS lookup for multidrop
1786 checkalias m Do comparison by IP address for
1787 multidrop
1788 no checkalias m Do comparison by name for mul‐
1789 tidrop (default)
1790 uidl -U Force POP3 to use client-side
1791 UIDLs (recommended)
1792 no uidl Turn off POP3 use of client-side
1793 UIDLs (default)
1794 interval Only check this site every N poll
1796 cycles; N is a numeric argument.
1797 tracepolls Add poll tracing information to
1798 the Received header
1799 principal Set Kerberos principal (only use‐
1800 ful with IMAP and kerberos)
1801 esmtpname Set name for RFC2554 authentica‐
1802 tion to the ESMTP server.
1803 esmtppassword Set password for RFC2554 authenti‐
1804 cation to the ESMTP server.
1805 bad-header How to treat messages with a bad
1806 header. Can be reject (default) or
1807 accept.
1808 Here are the legal user descriptions and options:
1810 Keyword Opt Mode Function
1813 ───────────────────────────────────────────────────────────────────────────────
1814 user[name] -u This is the user description and
1815 must come first after server de‐
1816 scription and after possible
1817 server options, and before user
1818 options.
1819 It sets the remote user name if by
1821 itself or followed by 'there', or
1822 the local user name if followed by
1823 'here'.
1824 is Connect local and remote user
1825 names
1826 to Connect local and remote user
1827 names
1828 pass[word] Specify remote account password
1829 ssl Connect to server over the speci‐
1830 fied base protocol using SSL en‐
1831 cryption
1832 sslcert Specify file for client side pub‐
1833 lic SSL certificate
1834 sslcertck Enable strict certificate checking
1835 and abort connection on failure.
1836 Default only since fetchmail
1837 v6.4.0.
1838 no sslcertck Disable strict certificate check‐
1839 ing and permit connections to con‐
1840 tinue on failed verification. Dis‐
1841 couraged. Should only be used to‐
1842 gether with sslfingerprint.
1843 sslcertfile Specify file with trusted CA cer‐
1844 tificates
1845 sslcertpath Specify c_rehash-ed directory with
1846 trusted CA certificates.
1847 sslfingerprint Specify the ex‐
1848 pected server
1849 certificate fin‐
1850 ger print from
1851 an MD5 hash.
1852 Fetchmail will
1853 disconnect and
1854 log an error if
1855 it does not
1856 match.
1857 sslkey Specify file for client side pri‐
1858 vate SSL key
1859 sslproto Force ssl protocol for connection
1860 folder -r Specify remote folder to query
1861 smtphost -S Specify smtp host(s) to forward to
1862 fetchdomains m Specify domains for which mail
1863 should be fetched
1864 smtpaddress -D Specify the domain to be put in
1866 RCPT TO lines
1867 smtpname Specify the user and domain to be
1868 put in RCPT TO lines
1869 antispam -Z Specify what SMTP returns are in‐
1870 terpreted as spam-policy blocks
1871 mda -m Specify MDA for local delivery
1872 bsmtp Specify BSMTP batch file to append
1873 to
1874 preconnect Command to be executed before each
1875 connection
1876 postconnect Command to be executed after each
1877 connection
1878 keep -k Do not delete seen messages from
1879 server (for POP3, uidl is recom‐
1880 mended)
1881 flush -F Flush all seen messages before
1882 querying (DANGEROUS)
1883 limitflush Flush all oversized messages be‐
1884 fore querying
1885 fetchall -a Fetch all messages whether seen or
1886 not
1887 rewrite Rewrite destination addresses for
1888 reply (default)
1889 stripcr Strip carriage returns from ends
1890 of lines
1891 forcecr Force carriage returns at ends of
1892 lines
1893 pass8bits Force BODY=8BITMIME to ESMTP lis‐
1894 tener
1895 dropstatus Strip Status and X-Mozilla-Status
1896 lines out of incoming mail
1897 dropdelivered Strip Delivered-To lines out of
1898 incoming mail
1899 mimedecode Convert quoted-printable to 8-bit
1900 in MIME messages
1901 idle Idle waiting for new messages af‐
1902 ter each poll (IMAP only)
1903 no keep -K Delete seen messages from server
1904 (default)
1905 no flush Do not flush all seen messages be‐
1906 fore querying (default)
1907 no fetchall Retrieve only new messages (de‐
1908 fault)
1909 no rewrite Do not rewrite headers
1910 no stripcr Do not strip carriage returns (de‐
1911 fault)
1912 no forcecr Do not force carriage returns at
1913 EOL (default)
1914 no pass8bits Do not force BODY=8BITMIME to
1915 ESMTP listener (default)
1916 no dropstatus Do not drop Status headers (de‐
1917 fault)
1918 no dropdelivered Do not drop Delivered-To headers
1919 (default)
1920 no mimedecode Do not convert quoted-printable to
1921 8-bit in MIME messages (default)
1922 no idle Do not idle waiting for new mes‐
1923 sages after each poll (IMAP only)
1924 limit -l Set message size limit
1925 warnings -w Set message size warning interval
1926 batchlimit -b Max # messages to forward in sin‐
1927 gle connect
1928 fetchlimit -B Max # messages to fetch in single
1929 connect
1930 fetchsizelimit Max # message sizes to fetch in
1931 single transaction
1932 fastuidl Use binary search for first unseen
1933 message (POP3 only)
1934 expunge -e Perform an expunge on every #th
1936 message (IMAP and POP3 only)
1937 properties String value is ignored by fetch‐
1938 mail (may be used by extension
1939 scripts)
1940 All user options must begin with a user description (user or username
1942 option) and follow all server descriptions and options.
1943 In the .fetchmailrc file, the 'envelope' string argument may be pre‐
1945 ceded by a whitespace-separated number. This number, if specified, is
1946 the number of such headers to skip over (that is, an argument of 1 se‐
1947 lects the second header of the given type). This is sometimes useful
1948 for ignoring bogus envelope headers created by an ISP's local delivery
1949 agent or internal forwards (through mail inspection systems, for in‐
1950 stance).
1951 Keywords Not Corresponding To Option Switches
1953 The 'folder' and 'smtphost' options (unlike their command-line equiva‐
1954 lents) can take a space- or comma-separated list of names following
1955 them.
1956 All options correspond to the obvious command-line arguments, except
1958 the following: 'via', 'interval', 'aka', 'is', 'to', 'dns'/'no dns',
1959 'checkalias'/'no checkalias', 'password', 'preconnect', 'postconnect',
1960 'localdomains', 'stripcr'/'no stripcr', 'forcecr'/'no forcecr',
1961 'pass8bits'/'no pass8bits' 'dropstatus/no dropstatus', 'dropdeliv‐
1962 ered/no dropdelivered', 'mimedecode/no mimedecode', 'no idle', and 'no
1963 envelope'.
1964 The 'via' option is for if you want to have more than one configuration
1966 pointing at the same site. If it is present, the string argument will
1967 be taken as the actual DNS name of the mail server host to query. This
1968 will override the argument of poll, which can then simply be a distinct
1969 label for the configuration (e.g., what you would give on the command
1970 line to explicitly query this host).
1971 The 'interval' option (which takes a numeric argument) allows you to
1973 poll a server less frequently than the basic poll interval. If you say
1974 'interval N' the server this option is attached to will only be queried
1975 every N poll intervals.
1976 Singledrop versus Multidrop options
1978 Please ensure you read the section titled THE USE AND ABUSE OF MUL‐
1979 TIDROP MAILBOXES if you intend to use multidrop mode.
1980 The 'is' or 'to' keywords associate the following local (client)
1982 name(s) (or server-name to client-name mappings separated by =) with
1983 the mail server user name in the entry. If an is/to list has '*' as
1984 its last name, unrecognized names are simply passed through. Note that
1985 until fetchmail version 6.3.4 inclusively, these lists could only con‐
1986 tain local parts of user names (fetchmail would only look at the part
1987 before the @ sign). fetchmail versions 6.3.5 and newer support full ad‐
1988 dresses on the left hand side of these mappings, and they take prece‐
1989 dence over any 'localdomains', 'aka', 'via' or similar mappings.
1990 A single local name can be used to support redirecting your mail when
1992 your username on the client machine is different from your name on the
1993 mail server. When there is only a single local name, mail is forwarded
1994 to that local username regardless of the message's Received, To, Cc,
1995 and Bcc headers. In this case, fetchmail never does DNS lookups.
1996 When there is more than one local name (or name mapping), fetchmail
1998 looks at the envelope header, if configured, and otherwise at the Re‐
1999 ceived, To, Cc, and Bcc headers of retrieved mail (this is 'multidrop
2000 mode'). It looks for addresses with host name parts that match your
2001 poll name or your 'via', 'aka' or 'localdomains' options, and usually
2002 also for host name parts which DNS tells it are aliases of the mail
2003 server. See the discussion of 'dns', 'checkalias', 'localdomains', and
2004 'aka' for details on how matching addresses are handled.
2005 If fetchmail cannot match any mail server usernames or localdomain ad‐
2007 dresses, the mail will be bounced. Normally it will be bounced to the
2008 sender, but if the 'bouncemail' global option is off, the mail will go
2009 to the local postmaster instead. (see the 'postmaster' global option).
2010 See also BUGS.
2011 The 'dns' option (normally on) controls the way addresses from mul‐
2013 tidrop mailboxes are checked. On, it enables logic to check each host
2014 address that does not match an 'aka' or 'localdomains' declaration by
2015 looking it up with DNS. When a mail server username is recognized at‐
2016 tached to a matching host name part, its local mapping is added to the
2017 list of local recipients.
2018 The 'checkalias' option (normally off) extends the lookups performed by
2020 the 'dns' keyword in multidrop mode, providing a way to cope with re‐
2021 mote MTAs that identify themselves using their canonical name, while
2022 they are polled using an alias. When such a server is polled, checks
2023 to extract the envelope address fail, and fetchmail reverts to delivery
2024 using the To/Cc/Bcc headers (See below 'Header versus Envelope ad‐
2025 dresses'). Specifying this option instructs fetchmail to retrieve all
2026 the IP addresses associated with both the poll name and the name used
2027 by the remote MTA and to do a comparison of the IP addresses. This
2028 comes in handy in situations where the remote server undergoes frequent
2029 canonical name changes, that would otherwise require modifications to
2030 the rcfile. 'checkalias' has no effect if 'no dns' is specified in the
2031 rcfile.
2032 The 'aka' option is for use with multidrop mailboxes. It allows you to
2034 pre-declare a list of DNS aliases for a server. This is an optimiza‐
2035 tion hack that allows you to trade space for speed. When fetchmail,
2036 while processing a multidrop mailbox, grovels through message headers
2037 looking for names of the mail server, pre-declaring common ones can
2038 save it from having to do DNS lookups. Note: the names you give as ar‐
2039 guments to 'aka' are matched as suffixes -- if you specify (say) 'aka
2040 netaxs.com', this will match not just a host name netaxs.com, but any
2041 host name that ends with '.netaxs.com'; such as (say) pop3.netaxs.com
2042 and mail.netaxs.com.
2043 The 'localdomains' option allows you to declare a list of domains which
2045 fetchmail should consider local. When fetchmail is parsing address
2046 lines in multidrop modes, and a trailing segment of a host name matches
2047 a declared local domain, that address is passed through to the listener
2048 or MDA unaltered (local-name mappings are not applied).
2049 If you are using 'localdomains', you may also need to specify 'no enve‐
2051 lope', which disables fetchmail's normal attempt to deduce an envelope
2052 address from the Received line or X-Envelope-To header or whatever
2053 header has been previously set by 'envelope'. If you set 'no envelope'
2054 in the defaults entry it is possible to undo that in individual entries
2055 by using 'envelope <string>'. As a special case, 'envelope "Received"'
2056 restores the default parsing of Received lines.
2057 The password option requires a string argument, which is the password
2059 to be used with the entry's server.
2060 The 'preconnect' keyword allows you to specify a shell command to be
2062 executed just before each time fetchmail establishes a mail server con‐
2063 nection. This may be useful if you are attempting to set up secure POP
2064 connections with the aid of ssh(1). If the command returns a nonzero
2065 status, the poll of that mail server will be aborted.
2066 Similarly, the 'postconnect' keyword similarly allows you to specify a
2068 shell command to be executed just after each time a mail server connec‐
2069 tion is taken down.
2070 The 'forcecr' option controls whether lines terminated by LF only are
2072 given CRLF termination before forwarding. Strictly speaking RFC821 re‐
2073 quires this, but few MTAs enforce the requirement so this option is
2074 normally off (only one such MTA, qmail, is in significant use at time
2075 of writing).
2076 The 'stripcr' option controls whether carriage returns are stripped out
2078 of retrieved mail before it is forwarded. It is normally not necessary
2079 to set this, because it defaults to 'on' (CR stripping enabled) when
2080 there is an MDA declared but 'off' (CR stripping disabled) when for‐
2081 warding is via SMTP. If 'stripcr' and 'forcecr' are both on, 'stripcr'
2082 will override.
2083 The 'pass8bits' option exists to cope with Microsoft mail programs that
2085 stupidly slap a "Content-Transfer-Encoding: 7bit" on everything. With
2086 this option off (the default) and such a header present, fetchmail de‐
2087 clares BODY=7BIT to an ESMTP-capable listener; this causes problems for
2088 messages actually using 8-bit ISO or KOI-8 character sets, which will
2089 be garbled by having the high bits of all characters stripped. If
2090 'pass8bits' is on, fetchmail is forced to declare BODY=8BITMIME to any
2091 ESMTP-capable listener. If the listener is 8-bit-clean (as all the ma‐
2092 jor ones now are) the right thing will probably result.
2093 The 'dropstatus' option controls whether nonempty Status and X-Mozilla-
2095 Status lines are retained in fetched mail (the default) or discarded.
2096 Retaining them allows your MUA to see what messages (if any) were
2097 marked seen on the server. On the other hand, it can confuse some new-
2098 mail notifiers, which assume that anything with a Status line in it has
2099 been seen. (Note: the empty Status lines inserted by some buggy POP
2100 servers are unconditionally discarded.)
2101 The 'dropdelivered' option controls whether Delivered-To headers will
2103 be kept in fetched mail (the default) or discarded. These headers are
2104 added by qmail and Postfix mail servers in order to avoid mail loops
2105 but may get in your way if you try to "mirror" a mail server within the
2106 same domain. Use with caution.
2107 The 'mimedecode' option controls whether MIME messages using the
2109 quoted-printable encoding are automatically converted into pure 8-bit
2110 data. If you are delivering mail to an ESMTP-capable, 8-bit-clean lis‐
2111 tener (that includes all of the major MTAs like sendmail), then this
2112 will automatically convert quoted-printable message headers and data
2113 into 8-bit data, making it easier to understand when reading mail. If
2114 your e-mail programs know how to deal with MIME messages, then this op‐
2115 tion is not needed. The mimedecode option is off by default, because
2116 doing RFC2047 conversion on headers throws away character-set informa‐
2117 tion and can lead to bad results if the encoding of the headers differs
2118 from the body encoding.
2119 The 'idle' option is intended to be used with IMAP servers supporting
2121 the RFC2177 IDLE command extension, but does not strictly require it.
2122 If it is enabled, and fetchmail detects that IDLE is supported, an IDLE
2123 will be issued at the end of each poll. This will tell the IMAP server
2124 to hold the connection open and notify the client when new mail is
2125 available. If IDLE is not supported, fetchmail will simulate it by pe‐
2126 riodically issuing NOOP. If you need to poll a link frequently, IDLE
2127 can save bandwidth by eliminating TCP/IP connects and LOGIN/LOGOUT se‐
2128 quences. On the other hand, an IDLE connection will eat almost all of
2129 your fetchmail's time, because it will never drop the connection and
2130 allow other polls to occur unless the server times out the IDLE. It
2131 also does not work with multiple folders; only the first folder will
2132 ever be polled.
2133 The 'properties' option is an extension mechanism. It takes a string
2135 argument, which is ignored by fetchmail itself. The string argument
2136 may be used to store configuration information for scripts which re‐
2137 quire it. In particular, the output of '--configdump' option will make
2138 properties associated with a user entry readily available to a Python
2139 script.
2140 Miscellaneous Run Control Options
2142 The words 'here' and 'there' have useful English-like significance.
2143 Normally 'user eric is esr' would mean that mail for the remote user
2144 'eric' is to be delivered to 'esr', but you can make this clearer by
2145 saying 'user eric there is esr here', or reverse it by saying 'user esr
2146 here is eric there'
2147 Legal protocol identifiers for use with the 'protocol' keyword are:
2149 auto (or AUTO) (legacy, to be removed from future release)
2151 pop2 (or POP2) (legacy, to be removed from future release)
2152 pop3 (or POP3)
2153 sdps (or SDPS)
2154 imap (or IMAP)
2155 apop (or APOP)
2156 kpop (or KPOP)
2157 Legal authentication types are 'any', 'password', 'kerberos', 'ker‐
2160 beros_v4', 'kerberos_v5' and 'gssapi', 'cram-md5', 'otp', 'msn' (only
2161 for POP3), 'ntlm', 'ssh', 'external' (only IMAP). The 'password' type
2162 specifies authentication by normal transmission of a password (the
2163 password may be plain text or subject to protocol-specific encryption
2164 as in CRAM-MD5); 'kerberos' tells fetchmail to try to get a Kerberos
2165 ticket at the start of each query instead, and send an arbitrary string
2166 as the password; and 'gssapi' tells fetchmail to use GSSAPI authentica‐
2167 tion. See the description of the 'auth' keyword for more.
2168 Specifying 'kpop' sets POP3 protocol over port 1109 with Kerberos V4
2170 authentication. These defaults may be overridden by later options.
2171 There are some global option statements: 'set logfile' followed by a
2173 string sets the same global specified by --logfile. A command-line
2174 --logfile option will override this. Note that --logfile is only effec‐
2175 tive if fetchmail detaches itself from the terminal and the logfile al‐
2176 ready exists before fetchmail is run, and it overrides --syslog in this
2177 case. Also, 'set daemon' sets the poll interval as --daemon does.
2178 This can be overridden by a command-line --daemon option; in particular
2179 --daemon 0 can be used to force foreground operation. The 'set postmas‐
2180 ter' statement sets the address to which multidrop mail defaults if
2181 there are no local matches. Finally, 'set syslog' sends log messages
2182 to syslogd(8).
2183
2186 Fetchmail crashing
2187 There are various ways in that fetchmail may "crash", i. e. stop opera‐
2188 tion suddenly and unexpectedly. A "crash" usually refers to an error
2189 condition that the software did not handle by itself. A well-known
2190 failure mode is the "segmentation fault" or "signal 11" or "SIGSEGV" or
2191 just "segfault" for short. These can be caused by hardware or by soft‐
2192 ware problems. Software-induced segfaults can usually be reproduced
2193 easily and in the same place, whereas hardware-induced segfaults can go
2194 away if the computer is rebooted, or powered off for a few hours, and
2195 can happen in random locations even if you use the software the same
2196 way.
2197 For solving hardware-induced segfaults, find the faulty component and
2199 repair or replace it. The Sig11 FAQ ⟨https://www.bitwizard.nl/sig11/⟩
2200 may help you with details.
2201 For solving software-induced segfaults, the developers may need a
2203 "stack backtrace".
2204 Enabling fetchmail core dumps
2207 By default, fetchmail suppresses core dumps as these might contain
2208 passwords and other sensitive information. For debugging fetchmail
2209 crashes, obtaining a "stack backtrace" from a core dump is often the
2210 quickest way to solve the problem, and when posting your problem on a
2211 mailing list, the developers may ask you for a "backtrace".
2212 1. To get useful backtraces, fetchmail needs to be installed without
2214 getting stripped of its compilation symbols. Unfortunately, most bi‐
2215 nary packages that are installed are stripped, and core files from sym‐
2216 bol-stripped programs are worthless. So you may need to recompile
2217 fetchmail. On many systems, you can type
2218 file `which fetchmail`
2220 to find out if fetchmail was symbol-stripped or not. If yours was un‐
2222 stripped, fine, proceed, if it was stripped, you need to recompile the
2223 source code first. You do not usually need to install fetchmail in or‐
2224 der to debug it.
2225 2. The shell environment that starts fetchmail needs to enable core
2227 dumps. The key is the "maximum core (file) size" that can usually be
2228 configured with a tool named "limit" or "ulimit". See the documentation
2229 for your shell for details. In the popular bash shell, "ulimit -Sc un‐
2230 limited" will allow the core dump.
2231 3. You need to tell fetchmail, too, to allow core dumps. To do this,
2233 run fetchmail with the -d0 -v options. It is often easier to also add
2234 --nosyslog -N as well.
2235 Finally, you need to reproduce the crash. You can just start fetchmail
2237 from the directory where you compiled it by typing ./fetchmail, so the
2238 complete command line will start with ./fetchmail -Nvd0 --nosyslog and
2239 perhaps list your other options.
2240 After the crash, run your debugger to obtain the core dump. The debug‐
2242 ger will often be GNU GDB, you can then type (adjust paths as neces‐
2243 sary) gdb ./fetchmail fetchmail.core and then, after GDB has started up
2244 and read all its files, type backtrace full, save the output (copy &
2245 paste will do, the backtrace will be read by a human) and then type
2246 quit to leave gdb. Note: on some systems, the core files have differ‐
2247 ent names, they might contain a number instead of the program name, or
2248 number and name, but it will usually have "core" as part of their name.
2249
2252 When trying to determine the originating address of a message, fetch‐
2253 mail looks through headers in the following order:
2254 Return-Path:
2256 Resent-Sender: (ignored if it does not contain an @ or !)
2257 Sender: (ignored if it does not contain an @ or !)
2258 Resent-From:
2259 From:
2260 Reply-To:
2261 Apparently-From:
2262 The originating address is used for logging, and to set the MAIL FROM
2264 address when forwarding to SMTP. This order is intended to cope grace‐
2265 fully with receiving mailing list messages in multidrop mode. The in‐
2266 tent is that if a local address does not exist, the bounce message will
2267 not be returned blindly to the author or to the list itself, but rather
2268 to the list manager (which is less annoying).
2269 In multidrop mode, destination headers are processed as follows: First,
2271 fetchmail looks for the header specified by the 'envelope' option in
2272 order to determine the local recipient address. If the mail is ad‐
2273 dressed to more than one recipient, the Received line will not contain
2274 any information regarding recipient addresses.
2275 Then fetchmail looks for the Resent-To:, Resent-Cc:, and Resent-Bcc:
2277 lines. If they exist, they should contain the final recipients and
2278 have precedence over their To:/Cc:/Bcc: counterparts. If the Resent-*
2279 lines do not exist, the To:, Cc:, Bcc: and Apparently-To: lines are
2280 looked for. (The presence of a Resent-To: is taken to imply that the
2281 person referred by the To: address has already received the original
2282 copy of the mail.)
2283
2286 Note that although there are password declarations in a good many of
2287 the examples below, this is mainly for illustrative purposes. We rec‐
2288 ommend stashing account/password pairs in your $HOME/.netrc file, where
2289 they can be used not just by fetchmail but by ftp(1) and other pro‐
2290 grams.
2291 The basic format is:
2293 poll SERVERNAME protocol PROTOCOL username NAME password PASS‐
2296 WORD
2297 Example:
2300 poll pop.provider.net protocol pop3 username "jsmith" password "secret1"
2303 Or, using some abbreviations:
2306 poll pop.provider.net proto pop3 user "jsmith" password "secret1"
2309 Multiple servers may be listed:
2312 poll pop.provider.net proto pop3 user "jsmith" pass "secret1"
2315 poll other.provider.net proto pop2 user "John.Smith" pass "My^Hat"
2316 Here is the same version with more whitespace and some noise words:
2319 poll pop.provider.net proto pop3
2322 user "jsmith", with password secret1, is "jsmith" here;
2323 poll other.provider.net proto pop2:
2324 user "John.Smith", with password "My^Hat", is "John.Smith" here;
2325 If you need to include whitespace in a parameter string or start the
2328 latter with a number, enclose the string in double quotes. Thus:
2329 poll mail.provider.net with proto pop3:
2332 user "jsmith" there has password "4u but u cannot krak this"
2333 is jws here and wants mda "/bin/mail"
2334 You may have an initial server description headed by the keyword 'de‐
2337 faults' instead of 'poll' followed by a name. Such a record is inter‐
2338 preted as defaults for all queries to use. It may be overwritten by in‐
2339 dividual server descriptions. So, you could write:
2340 defaults proto pop3
2343 user "jsmith"
2344 poll pop.provider.net
2345 pass "secret1"
2346 poll mail.provider.net
2347 user "jjsmith" there has password "secret2"
2348 It is possible to specify more than one user per server. The 'user'
2351 keyword leads off a user description, and every user specification in a
2352 multi-user entry must include it. Here is an example:
2353 poll pop.provider.net proto pop3 port 3111
2356 user "jsmith" with pass "secret1" is "smith" here
2357 user jones with pass "secret2" is "jjones" here keep
2358 This associates the local username 'smith' with the pop.provider.net
2361 username 'jsmith' and the local username 'jjones' with the
2362 pop.provider.net username 'jones'. Mail for 'jones' is kept on the
2363 server after download.
2364 Here is what a simple retrieval configuration for a multidrop mailbox
2367 looks like:
2368 poll pop.provider.net:
2371 user maildrop with pass secret1 to golux 'hurkle'='happy' snark here
2372 This says that the mailbox of account 'maildrop' on the server is a
2375 multidrop box, and that messages in it should be parsed for the server
2376 user names 'golux', 'hurkle', and 'snark'. It further specifies that
2377 'golux' and 'snark' have the same name on the client as on the server,
2378 but mail for server user 'hurkle' should be delivered to client user
2379 'happy'.
2380 Note that fetchmail, until version 6.3.4, did NOT allow full user@do‐
2383 main specifications here, these would never match. Fetchmail 6.3.5 and
2384 newer support user@domain specifications on the left-hand side of a
2385 user mapping.
2386 Here is an example of another kind of multidrop connection:
2389 poll pop.provider.net localdomains loonytoons.org toons.org
2392 envelope X-Envelope-To
2393 user maildrop with pass secret1 to * here
2394 This also says that the mailbox of account 'maildrop' on the server is
2397 a multidrop box. It tells fetchmail that any address in the loony‐
2398 toons.org or toons.org domains (including sub-domain addresses like
2399 'joe@daffy.loonytoons.org') should be passed through to the local SMTP
2400 listener without modification. Be careful of mail loops if you do
2401 this!
2402 Here is an example configuration using ssh and the plugin option. The
2405 queries are made directly on the stdin and stdout of imapd via ssh.
2406 Note that in this setup, IMAP authentication can be skipped.
2407 poll mailhost.net with proto imap:
2410 plugin "ssh %h /usr/sbin/imapd" auth ssh;
2411 user esr is esr here
2412
2415 Use the multiple-local-recipients feature with caution -- it can bite.
2416 All multidrop features are ineffective in ETRN and ODMR modes.
2417 Also, note that in multidrop mode duplicate mails may be suppressed. A
2419 piece of mail is considered duplicate if it does not have a discernible
2420 envelope recipient address, has the same header as the message immedi‐
2421 ately preceding and more than one addressee. Such runs of messages may
2422 be generated when copies of a message addressed to multiple users are
2423 delivered to a multidrop box. (To be precise, fetchmail 6.2.5 through
2424 6.4.X use an MD5 hash of the raw message header, and only fetchmail
2425 6.4.16+ document this properly. Fetchmail 5.0.8 (1999-09-14) through
2426 6.2.4 used only the Message-ID header. 5.0.7 and older did not sup‐
2427 press duplicates.)
2428 Note that this duplication killer code checking the entire header is
2430 very restrictive and may not suppress many duplicates in practice - for
2431 instance, if some X-Original-To or Delivered-To header differs. This
2432 is intentional and correct in such situations: wherever envelope infor‐
2433 mation is available, it should be used for reliable delivery of mailing
2434 list and blind carbon copy (Bcc) messages. See the subsection Duplicate
2435 suppression below for suggestions.
2436 Header versus Envelope addresses
2439 The fundamental problem is that by having your mail server toss several
2440 peoples' mail in a single maildrop box, you may have thrown away poten‐
2441 tially vital information about who each piece of mail was actually ad‐
2442 dressed to (the 'envelope address', as opposed to the header addresses
2443 in the RFC822 To/Cc headers - the Bcc is not available at the receiving
2444 end). This 'envelope address' is the address you need in order to
2445 reroute mail properly.
2446 Sometimes fetchmail can deduce the envelope address. If the mail
2448 server MTA is sendmail and the item of mail had just one recipient, the
2449 MTA will have written a 'by/for' clause that gives the envelope ad‐
2450 dressee into its Received header. But this does not work reliably for
2451 other MTAs, nor if there is more than one recipient. By default,
2452 fetchmail looks for envelope addresses in these lines; you can restore
2453 this default with -E "Received" or 'envelope Received'.
2454 As a better alternative, some SMTP listeners and/or mail servers insert
2456 a header in each message containing a copy of the envelope addresses.
2457 This header (when it exists) is often 'X-Original-To', 'Delivered-To'
2458 or 'X-Envelope-To'. Fetchmail's assumption about this can be changed
2459 with the -E or 'envelope' option. Note that writing an envelope header
2460 of this kind exposes the names of recipients (including blind-copy re‐
2461 cipients) to all receivers of the messages, so the upstream must store
2462 one copy of the message per recipient to avoid becoming a privacy prob‐
2463 lem.
2464 Postfix, since version 2.0, writes an X-Original-To: header which con‐
2466 tains a copy of the envelope as it was received.
2467 Qmail and Postfix generally write a 'Delivered-To' header upon deliver‐
2469 ing the message to the mail spool and use it to avoid mail loops.
2470 Qmail virtual domains however will prefix the user name with a string
2471 that normally matches the user's domain. To remove this prefix you can
2472 use the -Q or 'qvirtual' option.
2473 Sometimes, unfortunately, neither of these methods works. That is the
2475 point when you should contact your ISP and ask them to provide such an
2476 envelope header, and you should not use multidrop in this situation.
2477 When they all fail, fetchmail must fall back on the contents of To/Cc
2478 headers (Bcc headers are not available - see below) to try to determine
2479 recipient addressees -- and these are unreliable. In particular, mail‐
2480 ing-list software often ships mail with only the list broadcast address
2481 in the To: header.
2482 Note that a future version of fetchmail may remove To/Cc parsing!
2484 When fetchmail cannot deduce a recipient address that is local, and the
2486 intended recipient address was anyone other than fetchmail's invoking
2487 user, mail will get lost. This is what makes the multidrop feature
2488 risky without proper envelope information.
2489 A related problem is that when you blind-copy a mail message, the Bcc
2491 information is carried only as envelope address (it is removed from the
2492 headers by the sending mail server, so fetchmail can see it only if
2493 there is an X-Envelope-To header). Thus, blind-copying to someone who
2494 gets mail over a fetchmail multidrop link will fail unless the mail
2495 server host routinely writes X-Envelope-To or an equivalent header into
2496 messages in your maildrop.
2497 In conclusion, mailing lists and Bcc'd mail can only work if the server
2499 you are fetching from
2500 (1) stores one copy of the message per recipient in your domain and
2502 (2) records the envelope information in a special header (X-Origi‐
2504 nal-To, Delivered-To, X-Envelope-To).
2505 Good Ways To Use Multidrop Mailboxes
2508 Multiple local names can be used to administer a mailing list from the
2509 client side of a fetchmail collection. Suppose your name is 'esr', and
2510 you want to both pick up your own mail and maintain a mailing list
2511 called (say) "fetchmail-friends", and you want to keep the alias list
2512 on your client machine.
2513 On your server, you can alias 'fetchmail-friends' to 'esr'; then, in
2515 your .fetchmailrc, declare 'to esr fetchmail-friends here'. Then, when
2516 mail including 'fetchmail-friends' as a local address gets fetched, the
2517 list name will be appended to the list of recipients your SMTP listener
2518 sees. Therefore it will undergo alias expansion locally. Be sure to
2519 include 'esr' in the local alias expansion of fetchmail-friends, or you
2520 will never see mail sent only to the list. Also be sure that your lis‐
2521 tener has the "me-too" option set (sendmail's -oXm command-line option
2522 or OXm declaration) so your name is not removed from alias expansions
2523 in messages you send.
2524 This trick is not without its problems, however. You will begin to see
2526 this when a message comes in that is addressed only to a mailing list
2527 you do not have declared as a local name. Each such message will fea‐
2528 ture an 'X-Fetchmail-Warning' header which is generated because fetch‐
2529 mail cannot find a valid local name in the recipient addresses. Such
2530 messages default (as was described above) to being sent to the local
2531 user running fetchmail, but the program has no way to know that this is
2532 actually the right thing.
2533 Bad Ways To Abuse Multidrop Mailboxes
2536 Multidrop mailboxes and fetchmail serving multiple users in daemon mode
2537 do not mix. The problem, again, is mail from mailing lists, which typ‐
2538 ically does not have an individual recipient address on it. Unless
2539 fetchmail can deduce an envelope address, such mail will only go to the
2540 account running fetchmail (probably root). Also, blind-copied users
2541 are very likely never to see their mail at all.
2542 If you are tempted to use fetchmail to retrieve mail for multiple users
2544 from a single mail drop via POP or IMAP, think again (and reread the
2545 section on header and envelope addresses above). It would be smarter
2546 to just let the mail sit in the mail server's queue and use fetchmail's
2547 ETRN or ODMR modes to trigger SMTP sends periodically (of course, this
2548 means you have to poll more frequently than the mail server's expiry
2549 period). If you cannot arrange this, try setting up a UUCP feed.
2550 If you absolutely must use multidrop for this purpose, make sure your
2552 mail server writes an envelope-address header that fetchmail can see.
2553 Otherwise you will lose mail and it will come back to haunt you.
2554 Speeding Up Multidrop Checking
2557 Normally, when multiple users are declared fetchmail extracts recipient
2558 addresses as described above and checks each host part with DNS to see
2559 if it is an alias of the mail server. If so, the name mappings de‐
2560 scribed in the "to ... here" declaration are done and the mail locally
2561 delivered.
2562 This is a convenient but also slow method. To speed it up, pre-declare
2564 mail server aliases with 'aka'; these are checked before DNS lookups
2565 are done. If you are certain your aka list contains all DNS aliases of
2566 the mail server (and all MX names pointing at it - note this may change
2567 in a future version) you can declare 'no dns' to suppress DNS lookups
2568 entirely and only match against the aka list.
2569 Duplicate suppression on multidrop
2572 If fetchmail's duplicate suppression code does not kick in for your
2573 multidrop mail account, other options is using sieve, or for instance
2574 Courier's maildrop package (and in particular, its reformail program
2575 with the -D option) as the delivery agent (either from fetchmail, or
2576 from your local mail server that fetchmail injects into).
2577
2580 Support for socks4/5 is a compile time configuration option. Once com‐
2581 piled in, fetchmail will always use the socks libraries and configura‐
2582 tion on your system, there are no run-time switches in fetchmail - but
2583 you can still configure SOCKS: you can specify which SOCKS configura‐
2584 tion file is used in the SOCKS_CONF environment variable.
2585 For instance, if you wanted to bypass the SOCKS proxy altogether and
2587 have fetchmail connect directly, you could just pass
2588 SOCKS_CONF=/dev/null in the environment, for example (add your usual
2589 command line options - if any - to the end of this line):
2590 env SOCKS_CONF=/dev/null fetchmail
2592
2595 To facilitate the use of fetchmail in shell scripts, an exit status
2596 code is returned to give an indication of what occurred during a given
2597 connection.
2598 The exit codes returned by fetchmail are as follows:
2600 0 One or more messages were successfully retrieved (or, if the -c
2602 option was selected, were found waiting but not retrieved).
2603 1 There was no mail awaiting retrieval. (There may have been old
2605 mail still on the server but not selected for retrieval.) If you
2606 do not want "no mail" to be an error condition (for instance,
2607 for cron jobs), use a POSIX-compliant shell and add
2608 || [ $? -eq 1 ]
2610 to the end of the fetchmail command line, note that this leaves
2612 0 untouched, maps 1 to 0, and maps all other codes to 1. See
2613 also item #C8 in the FAQ.
2614 2 An error was encountered when attempting to open a socket to re‐
2616 trieve mail. If you do not know what a socket is, do not worry
2617 about it -- just treat this as an 'unrecoverable error'. This
2618 error can also be because a protocol fetchmail wants to use is
2619 not listed in /etc/services.
2620 3 The user authentication step failed. This usually means that a
2622 bad user-id, password, or APOP id was specified. Or it may mean
2623 that you tried to run fetchmail under circumstances where it did
2624 not have standard input attached to a terminal and could not
2625 prompt for a missing password.
2626 4 Some sort of fatal protocol error was detected.
2628 5 There was a syntax error in the arguments to fetchmail, or a
2630 pre- or post-connect command failed.
2631 6 The run control file had bad permissions.
2633 7 There was an error condition reported by the server. Can also
2635 fire if fetchmail timed out while waiting for the server.
2636 8 Client-side exclusion error. This means fetchmail either found
2638 another copy of itself already running, or failed in such a way
2639 that it is not sure whether another copy is running.
2640 9 The user authentication step failed because the server responded
2642 "lock busy". Try again after a brief pause! This error is not
2643 implemented for all protocols, nor for all servers. If not im‐
2644 plemented for your server, "3" will be returned instead, see
2645 above. May be returned when talking to qpopper or other servers
2646 that can respond with "lock busy" or some similar text contain‐
2647 ing the word "lock".
2648 10 The fetchmail run failed while trying to do an SMTP port open or
2650 transaction.
2651 11 Fatal DNS error. Fetchmail encountered an error while perform‐
2653 ing a DNS lookup at startup and could not proceed.
2654 12 BSMTP batch file could not be opened.
2656 13 Poll terminated by a fetch limit (see the --fetchlimit option).
2658 14 Server busy indication.
2660 23 Internal error. You should see a message on standard error with
2662 details.
2663 24 - 26, 28, 29
2665 These are internal codes and should not appear externally.
2666 When fetchmail queries more than one host, return status is 0 if any
2668 query successfully retrieved mail. Otherwise the returned error status
2669 is that of the last host queried.
2670
2673 ~/.fetchmailrc, $HOME/.fetchmailrc, $HOME_ETC/.fetchmailrc, $FETCHMAIL‐
2674 HOME/fetchmailrc
2675 default run control file (location can be overridden with environ‐
2676 ment variables)
2677 ~/.fetchids, $HOME/.fetchids, $HOME_ETC/.fetchids, $FETCHMAIL‐
2679 HOME/.fetchids
2680 default location of file recording last message UIDs seen per
2681 host. (location can be overridden with environment variables)
2682 ~/.fetchmail.pid, $HOME/.fetchmail.pid, $HOME_ETC/.fetchmail.pid,
2684 $FETCHMAILHOME/fetchmail.pid
2685 default location of lock file (sometimes called pidfile or PID
2686 file, see option pidfile) to help prevent concurrent runs (non-
2687 root mode). (location can be overridden with environment vari‐
2688 ables)
2689 ~/.netrc, $HOME/.netrc, $HOME_ETC/.netrc
2691 your FTP run control file, which (if present) will be searched for
2692 passwords as a last resort before prompting for one interactively.
2693 (location can be overridden with environment variables)
2694 /var/run/fetchmail.pid
2696 lock file (pidfile) to help prevent concurrent runs (root mode,
2697 Linux systems).
2698 /etc/fetchmail.pid
2700 lock file (pidfile) to help prevent concurrent runs (root mode,
2701 systems without /var/run).
2702
2705 Fetchmail's behavior can be altered by providing it with environment
2706 variables. Some may alter the operation of libraries that fetchmail
2707 links against, for instance, OpenSSL. Note that in daemon mode, you
2708 will need to quit the background daemon process and start a new fetch‐
2709 mail daemon for environment changes to take effect.
2710 FETCHMAILHOME
2712 If this environment variable is set to a valid and existing di‐
2713 rectory name, fetchmail will read $FETCHMAILHOME/fetchmailrc
2714 (the dot is missing in this case), $FETCHMAILHOME/.fetchids
2715 (keeping its dot) and $FETCHMAILHOME/fetchmail.pid (without dot)
2716 rather than from the user's home directory. The .netrc file is
2717 always looked for in the invoking user's home directory (or
2718 $HOME_ETC) regardless of FETCHMAILHOME's setting.
2719 FETCHMAILUSER
2722 If this environment variable is set, it is used as the name of
2723 the calling user (default local name) for purposes such as mail‐
2724 ing error notifications. Otherwise, if either the LOGNAME or
2725 USER variable is correctly set (e.g., the corresponding UID
2726 matches the session user ID) then that name is used as the de‐
2727 fault local name. Otherwise getpwuid(3) must be able to re‐
2728 trieve a password entry for the session ID (this elaborate logic
2729 is designed to handle the case of multiple names per user ID
2730 gracefully).
2731 FETCHMAIL_DISABLE_CBC_IV_COUNTERMEASURE
2734 (since v6.3.22): If this environment variable is set and not
2735 empty, fetchmail will disable a countermeasure against an SSL
2736 CBC IV attack (by setting SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS).
2737 This is a security risk, but may be necessary for connecting to
2738 certain non-standards-conforming servers. See fetchmail's NEWS
2739 file and fetchmail-SA-2012-01.txt for details. Earlier fetch‐
2740 mail versions (v6.3.21 and older) used to disable this counter‐
2741 measure, but v6.3.22 no longer does that as a safety precaution.
2742 FETCHMAIL_POP3_FORCE_RETR
2745 (since v6.3.9): If this environment variable is defined at all
2746 (even if empty), fetchmail will forgo the POP3 TOP command and
2747 always use RETR. This can be used as a workaround when TOP does
2748 not work properly.
2749 FETCHMAIL_INCLUDE_DEFAULT_X509_CA_CERTS
2752 (since v6.3.17): If this environment variable is set and not
2753 empty, fetchmail will always load the default X.509 trusted cer‐
2754 tificate locations for SSL/TLS CA certificates, even if
2755 --sslcertfile and --sslcertpath are given. The latter locations
2756 take precedence over the system default locations. This is use‐
2757 ful in case there are broken certificates in the system directo‐
2758 ries and the user has no administrator privileges to remedy the
2759 problem.
2760 FETCHMAIL_WOLFSSL_DEBUG
2763 (since v6.4.25): If fetchmail is compiled and linked with wolf‐
2764 SSL, if wolfSSL was built with --enable-debug, and if this envi‐
2765 ronment variable is set and not empty, then enable wolfSSL's de‐
2766 bug mode. This will emit huge amounts of debug output to stderr.
2767 HOME (documented since 6.4.1): This variable is normally set to the
2770 user's home directory. If it is set to a different directory
2771 than what is in the password database, HOME takes precedence.
2772 HOME_ETC
2775 (documentation corrected to match behaviour of code since
2776 6.4.1): If the HOME_ETC variable is set, it will override fetch‐
2777 mail's idea of $HOME, i. e. fetchmail will read .fetchmailrc,
2778 .fetchids, .fetchmail.pid and .netrc from $HOME_ETC instead of
2779 $HOME (or if HOME is also unset, from the passwd file's home di‐
2780 rectory location).
2781 If HOME_ETC and FETCHMAILHOME are both set, FETCHMAILHOME takes
2783 precedence and HOME_ETC will be ignored.
2784 SOCKS_CONF
2787 (only if SOCKS support is compiled in) this variable is used by
2788 the socks library to find out which configuration file it should
2789 read. Set this to /dev/null to bypass the SOCKS proxy.
2790 SSL_CERT_DIR
2793 (with truly OpenSSL 1.1.1 compatible library): overrides
2794 OpenSSL's idea of the default trust directory or path (which
2795 contains individual certificate files and hashed symlinks), see
2796 the SSL_CTX_set_default_verify_paths(3) manual page for details,
2797 it may be in the openssl development package. If using another
2798 library's OpenSSL compatibility interface, this may not work.
2799 Since this variable only specifies a default value, the option
2800 --sslcertpath takes precedence if given.
2801 SSL_CERT_FILE
2804 (with truly OpenSSL 1.1.1 compatible library): overrides
2805 OpenSSL's idea of the default trust certificate bundle file
2806 (which contains a concatenation of base64-encoded certificates
2807 in PEM format), see the SSL_CTX_set_default_verify_paths(3) man‐
2808 ual page for details, it may be in the openssl development pack‐
2809 age. If using another library's OpenSSL compatibility inter‐
2810 face, this may not work. Since this variable only specifies a
2811 default value, the option --sslcertfile takes precedence if
2812 given.
2813
2816 If a fetchmail daemon is running as root, SIGUSR1 wakes it up from its
2817 sleep phase and forces a poll of all non-skipped servers. For compati‐
2818 bility reasons, SIGHUP can also be used in 6.3.X but may not be avail‐
2819 able in future fetchmail versions.
2820 If fetchmail is running in daemon mode as non-root, use SIGUSR1 to wake
2822 it (this is so SIGHUP due to logout can retain the default action of
2823 killing it).
2824 Running fetchmail in foreground while a background fetchmail is running
2826 will do whichever of these is appropriate to wake it up.
2827
2830 Please check the NEWS file that shipped with fetchmail for more known
2831 bugs than those listed here.
2832 Fetchmail cannot handle user names that contain blanks after a "@"
2834 character, for instance "demonstr@ti on". These are rather uncommon and
2835 only hurt when using UID-based --keep setups, so the 6.X.Y versions of
2836 fetchmail will not be fixed.
2837 Fetchmail cannot handle configurations where you have multiple accounts
2839 that use the same server name and the same login. Any user@server com‐
2840 bination must be unique.
2841 The assumptions that the DNS and in particular the checkalias options
2843 make are not often sustainable. For instance, it has become uncommon
2844 for an MX server to be a POP3 or IMAP server at the same time. There‐
2845 fore the MX lookups may go away in a future release.
2846 The mda and plugin options interact badly. In order to collect error
2848 status from the MDA, fetchmail has to change its normal signal handling
2849 so that dead plugin processes do not get reaped until the end of the
2850 poll cycle. This can cause resource starvation if too many zombies ac‐
2851 cumulate. So either do not deliver to a MDA using plugins or risk be‐
2852 ing overrun by an army of undead.
2853 The --interface option does not support IPv6 and it is doubtful if it
2855 ever will, since there is no portable way to query interface IPv6 ad‐
2856 dresses.
2857 The RFC822 address parser used in multidrop mode chokes on some @-ad‐
2859 dresses that are technically legal but bizarre. Strange uses of quot‐
2860 ing and embedded comments are likely to confuse it.
2861 In a message with multiple envelope headers, only the last one pro‐
2863 cessed will be visible to fetchmail.
2864 Use of some of these protocols requires that the program send unen‐
2866 crypted passwords over the TCP/IP connection to the mail server. This
2867 creates a risk that name/password pairs might be snaffled with a packet
2868 sniffer or more sophisticated monitoring software. Under Linux and
2869 FreeBSD, the --interface option can be used to restrict polling to
2870 availability of a specific interface device with a specific local or
2871 remote IP address, but snooping is still possible if (a) either host
2872 has a network device that can be opened in promiscuous mode, or (b) the
2873 intervening network link can be tapped. We recommend the use of ssh(1)
2874 tunnelling to not only shroud your passwords but encrypt the entire
2875 conversation.
2876 Use of the %F or %T escapes in an mda option could open a security
2878 hole, because they pass text manipulable by an attacker to a shell com‐
2879 mand. Potential shell characters are replaced by '_' before execution.
2880 The hole is further reduced by the fact that fetchmail temporarily dis‐
2881 cards any set-uid privileges it may have while running the MDA. For
2882 maximum safety, however, do not use an mda command containing %F or %T
2883 when fetchmail is run from the root account itself.
2884 Fetchmail's method of sending bounces due to errors or spam-blocking
2886 and spam bounces requires that port 25 of localhost be available for
2887 sending mail via SMTP.
2888 If you modify ~/.fetchmailrc while a background instance is running and
2890 break the syntax, the background instance will die silently. Unfortu‐
2891 nately, it cannot die noisily because we do not yet know whether syslog
2892 should be enabled. On some systems, fetchmail dies quietly even if
2893 there is no syntax error; this seems to have something to do with buggy
2894 terminal ioctl code in the kernel.
2895 The -f - option (reading a configuration from stdin) is incompatible
2897 with the plugin option.
2898 The 'principal' option only handles Kerberos IV, not V.
2900 Interactively entered passwords are truncated after 63 characters. If
2902 you really need to use a longer password, you will have to use a con‐
2903 figuration file.
2904 A backslash as the last character of a configuration file will be
2906 flagged as a syntax error rather than ignored.
2907 The BSMTP error handling is virtually nonexistent and may leave broken
2909 messages behind.
2910 Send comments, bug reports, gripes, and the like to the fetchmail-devel
2912 list ⟨mailto:fetchmail-devel@lists.sourceforge.net⟩
2913 An fetchmail FAQ (in HTML form)
2916 ⟨https://fetchmail.sourceforge.io/fetchmail-FAQ.html⟩ is available at
2917 the fetchmail home page, it should also accompany your installation.
2918
2921 Fetchmail is currently maintained by Matthias Andree and Rob Funk with
2922 major assistance from Sunil Shetye (for code) and Rob MacGregor (for
2923 the mailing lists).
2924 Most of the code is from Eric S. Raymond
2926 ⟨mailto:esr@snark.thyrsus.com⟩. Too many other people to name here
2927 have contributed code and patches.
2928 This program is descended from and replaces popclient, by Carl Harris
2930 ⟨mailto:ceharris@mal.com⟩; the internals have become quite different,
2931 but some of its interface design is directly traceable to that ances‐
2932 tral program.
2933 This manual page has been improved by Matthias Andree, R. Hannes Bein‐
2935 ert, and Héctor García.
2936
2939 README, README.SSL, README.SSL-SERVER, The Fetchmail FAQ
2940 ⟨https://www.fetchmail.info/fetchmail-FAQ.html⟩, mutt(1), elm(1),
2941 mail(1), sendmail(8), popd(8), imapd(8), netrc(5), the fetchmail home
2942 page ⟨https://www.fetchmail.info/⟩, (alternative URI)
2943 ⟨https://fetchmail.sourceforge.io/⟩; the maildrop home page.
2944 ⟨https://www.courier-mta.org/maildrop/⟩
2945
2947 Note that this list is just a collection of references and not a state‐
2948 ment as to the actual protocol conformance or requirements in fetch‐
2949 mail.
2950 SMTP/ESMTP:
2952 RFC 821, RFC 2821, RFC 1869, RFC 1652, RFC 1870, RFC 1983, RFC
2953 1985, RFC 2554.
2954 mail:
2956 RFC 822, RFC 2822, RFC 1123, RFC 1892, RFC 1894.
2957 POP2:
2959 RFC 937
2960 POP3:
2962 RFC 1081, RFC 1225, RFC 1460, RFC 1725, RFC 1734, RFC 1939, RFC
2963 1957, RFC 2195, RFC 2449.
2964 APOP:
2966 RFC 1939.
2967 RPOP:
2969 RFC 1081, RFC 1225.
2970 IMAP2/IMAP2BIS:
2972 RFC 1176, RFC 1732.
2973 IMAP4/IMAP4rev1:
2975 RFC 1730, RFC 1731, RFC 1732, RFC 2060, RFC 2061, RFC 2195, RFC
2976 2177, RFC 2683.
2977 ETRN:
2979 RFC 1985.
2980 ODMR/ATRN:
2982 RFC 2645.
2983 OTP: RFC 1938.
2985 LMTP:
2987 RFC 2033.
2988 GSSAPI:
2990 RFC 1508, RFC 1734, Generic Security Service Application Program
2991 Interface (GSSAPI)/Kerberos/Simple Authentication and Security
2992 Layer (SASL) Service Names
2993 ⟨https://www.iana.org/assignments/gssapi-service-names/⟩.
2994 TLS: RFC 2595.
2996fetchmail 6.4.37 2022-07-16 FETCHMAIL(1)