Manual Reference Pages  - fetchmail (1) (2024)

fetchmail - fetch mail from a POP, IMAP, ETRN, or ODMR-capable server

CONTENTS

Synopsis
Description
General Operation
General Options
Disposal Options
Protocol and Query Options
Delivery Control Options
Resource Limit Control Options
Authentication Options
Miscellaneous Options
User Authentication And Encryption
Daemon Mode
Administrative Options
Retrieval Failure Modes
Spam Filtering
Smtp/esmtp Error Handling
The Run Control File
Run Control Syntax
Poll vs. Skip
Keyword/Option Summary
Keywords Not Corresponding To Option Switches
Miscellaneous Run Control Options
Interaction With Rfc 822
Configuration Examples
The Use And Abuse Of Multidrop Mailboxes
Header vs. Envelope addresses
Good Ways To Use Multidrop Mailboxes
Bad Ways To Abuse Multidrop Mailboxes
Speeding Up Multidrop Checking
Exit Codes
Files
Environment
Signals
Bugs And Known Problems
Author
See Also
Applicable Standards

fetchmail [option...] [mailserver...]
fetchmailconf

fetchmail is a mail-retrieval and forwarding utility; it fetches mail fromremote mailservers and forwards it to your local (client) machine’sdelivery system. You can then handle the retrieved mail using normalmail user agents such as mutt(1), elm(1) or Mail(1).The fetchmail utility can be run in a daemon mode to repeatedlypoll one or more systems at a specified interval.

Thefetchmail program can gather mail from servers supporting any of the commonmail-retrieval protocols: POP2, POP3, IMAP2bis, IMAP4, and IMAPrev1.It can also use the ESMTP ETRN extension and ODMR. (The RFCs describing allthese protocols are listed at the end of this manual page.)

Whilefetchmail is primarily intended to be used over on-demand TCP/IP links (such asSLIP or PPP connections), it may also be useful as a message transferagent for sites which refuse for security reasons to permit(sender-initiated) SMTP transactions with sendmail.

As each message is retrieved fetchmail normally delivers it via SMTP toport 25 on the machine it is running on (localhost), just as though itwere being passed in over a normal TCP/IP link. The mail will then bedelivered locally via your system’s MDA (Mail Delivery Agent, usuallysendmail(8) but your system may use a different one suchas smail, mmdf, exim, or qmail). All thedelivery-control mechanisms (such as .forward files) normallyavailable through your system MDA and local delivery agents willtherefore work automatically.

If no port 25 listener is available, but your fetchmail configurationwas told about a reliable local MDA, it will use that MDA for localdelivery instead. At build time, fetchmail normally looks forexecutableprocmail(1)andsendmail(1)binaries.

If the programfetchmailconf is available, it will assist you in setting up and editing afetchmailrc configuration. It runs under X and requires that thelanguage Python and the Tk toolkit be present on your system. Ifyou are first setting up fetchmail for single-user mode, it isrecommended that you use Novice mode. Expert mode providescomplete control of fetchmail configuration, including themultidrop features. In either case, the ‘Autoprobe’ buttonwill tell you the most capable protocol a given mailserversupports, and warn you of potential problems with that server.

The behavior offetchmail is controlled by command-line options and a run control file,~/.fetchmailrc, the syntax of which we describe in a later section (this file is whatthe fetchmailconf program edits). Command-line options override~/.fetchmailrc declarations.

Each server name that you specify following the options on thecommand line will be queried. If you don’t specify any serverson the command line, each ‘poll’ entry in your~/.fetchmailrc file will be queried.

To facilitate the use offetchmail in scripts and pipelines, it returns an appropriate exit code upontermination -- see EXIT CODES below.

The following options modify the behavior of fetchmail. It isseldom necessary to specify any of these once you have aworking .fetchmailrc file set up.

Almost all options have a corresponding keyword which can be used todeclare them in a.fetchmailrc file.

Some special options are not covered here, but are documented insteadin sections on AUTHENTICATION and DAEMON MODE which follow.

-V | --version
	Displays the version information for your copy offetchmail. No mail fetch is performed.Instead, for each server specified, all the option informationthat would be computed iffetchmail were connecting to that server is displayed. Any non-printables inpasswords or other string names are shown as backslashed C-likeescape sequences. This option is useful for verifying that youroptions are set the way you want them.
-c | --check
	Return a status code to indicate whether there is mail waiting,without actually fetching or deleting mail (see EXIT CODES below).This option turns off daemon mode (in which it would be useless). Itdoesn’t play well with queries to multiple sites, and doesn’t workwith ETRN or ODMR. It will return a false positive if you leave read butundeleted mail in your server mailbox and your fetch protocol can’ttell kept messages from new ones. This means it will work with IMAP,not work with POP2, and may occasionally flake out under POP3.
-s | --silent
	Silent mode. Suppresses all progress/status messages that arenormally echoed to standard output during a fetch (but does notsuppress actual error messages). The --verbose option overrides this.
-v | --verbose
	Verbose mode. All control messages passed betweenfetchmail and the mailserver are echoed to stdout. Overrides --silent.Doubling this option (-v -v) causes extra diagnostic informationto be printed.

-a | --all	(Keyword: fetchall)Retrieve both old (seen) and new messages from the mailserver. Thedefault is to fetch only messages the server has not marked seen.Under POP3, this option also forces the use of RETR rather than TOP.Note that POP2 retrieval behaves as though --all is always on (seeRETRIEVAL FAILURE MODES below) and this option does not work with ETRNor ODMR.
-k | --keep
	(Keyword: keep)Keep retrieved messages on the remote mailserver. Normally, messagesare deleted from the folder on the mailserver after they have been retrieved.Specifying thekeep option causes retrieved messages to remain in your folder on themailserver. This option does not work with ETRN or ODMR.
-K | --nokeep
	(Keyword: nokeep)Delete retrieved messages from the remote mailserver. Thisoption forces retrieved mail to be deleted. It may be useful ifyou have specified a default of keep in your.fetchmailrc. This option is forced on with ETRN and ODMR.
-F | --flush
	POP3/IMAP only. Delete old (previously retrieved) messages from themailserver before retrieving new messages. This option does not workwith ETRN or ODMR. Warning: if your local MTA hangs and fetchmail isaborted, the next time you run fetchmail, it will delete mail that wasnever delivered to you. What you probably want is the defaultsetting: if you don’t specify ‘-k’, then fetchmail will automaticallydelete messages after successful delivery.

-p <proto> | --protocol <proto>
	(Keyword: proto[col])Specify the protocol to use when communicating with the remotemailserver. If no protocol is specified, the default is AUTO.proto may be one of the following: AUTO Tries IMAP, POP3, and POP2 (skipping any of these for which supporthas not been compiled in). POP2 Post Office Protocol 2 POP3 Post Office Protocol 3 APOP Use POP3 with old-fashioned MD5-challenge authentication. RPOP Use POP3 with RPOP authentication. KPOP Use POP3 with Kerberos V4 authentication on port 1109. SDPS Use POP3 with Demon Internet’s SDPS extensions. IMAP IMAP2bis, IMAP4, or IMAP4rev1 (fetchmail autodetects their capabilities). ETRN Use the ESMTP ETRN option. ODMR Use the the On-Demand Mail Relay ESMTP profile.
All these alternatives work in basically the same way (communicatingwith standard server daemons to fetch mail already delivered to amailbox on the server) except ETRN and ODMR. The ETRN modeallows you to ask a compliant ESMTP server (such as BSD sendmail atrelease 8.8.0 or higher) to immediately open a sender-SMTP connectionto your client machine and begin forwarding any items addressed toyour client machine in the server’s queue of undelivered mail. TheODMR mode requires an ODMR-capable server and works similarly toETRN, except that it does not require the client machine to havea static DNS.
-U | --uidl
	(Keyword: uidl)Force UIDL use (effective only with POP3). Force client-side trackingof ‘newness’ of messages (UIDL stands for ‘‘unique ID listing’’ and isdescribed in RFC1725). Use with ‘keep’ to use a mailbox as a babynews drop for a group of users. The fact that seen messages are skippedis logged, unless error logging is done through syslog while running indaemon mode.
-P <portnumber> | --port <portnumber>
	(Keyword: port)The port option permits you to specify a TCP/IP port to connect on.This option will seldom be necessary as all the supported protocols havewell-established default port numbers.
--principal <principal>
	(Keyword: principal)The principal option permits you to specify a service principal formutual authentication. This is applicable to POP3 or IMAP with Kerberosauthentication.
-t <seconds> | --timeout <seconds>
	(Keyword: timeout)The timeout option allows you to set a server-nonresponsetimeout in seconds. If a mailserver does not send a greeting messageor respond to commands for the given number of seconds,fetchmail will hang up on it. Without such a timeoutfetchmail might hang up indefinitely trying to fetch mail from adown host. This would be particularly annoying for a fetchmailrunning in background. There is a default timeout which fetchmail -Vwill report. If a given connection receives too many timeouts insuccession, fetchmail will consider it wedged and stop retrying,the calling user will be notified by email if this happens.
--plugin <command>
	(Keyword: plugin) The plugin option allows you to use an externalprogram to establish the TCP connection. This is useful if you wantto use socks, SSL, ssh, or need some special firewalling setup. Theprogram will be looked up in $PATH and can optionally be passed thehostname and port as arguments using "%h" and "%p" respectively (notethat the interpolation logic is rather primitive, and these token mustbe bounded by whitespace or beginning of string or end of string).Fetchmail will write to the plugin’s stdin and read from the plugin’sstdout.
--plugout <command>
	(Keyword: plugout)Identical to the plugin option above, but this one is used for the SMTPconnections (which will probably not need it, so it has been separatedfrom plugin).
-r <name> | --folder <name>
	(Keyword: folder[s])Causes a specified non-default mail folder on the mailserver (orcomma-separated list of folders) to be retrieved. The syntax of thefolder name is server-dependent. This option is not available underPOP3, ETRN, or ODMR.
--tracepolls
	(Keyword: tracepolls)Tell fetchail to poll trace information in the form ‘polling %saccount %s’ to the Received line it generates, where the %s parts arereplaced by the user’s remote name and the poll label (the Receivedheader also normally includes the server’s truename). This can beused to facilate mail filtering based on the account it is beingreceived from.
--ssl	(Keyword: ssl)Causes the connection to the mail server to be encrypted via SSL. Connectto the server using the specified base protocol over a connection securedby SSL. SSL support must be present at the server. If no port isspecified, the connection is attempted to the well known port of the SSLversion of the base protocol. This is generally a different port than theport used by the base protocol. For IMAP, this is port 143 for the clearprotocol and port 993 for the SSL secured protocol.
--sslcert <name>
	(Keyword: sslcert)Specifies the file name of the client side public SSL certificate. SomeSSL encrypted servers may require client side keys and certificates forauthentication. In most cases, this is optional. This specifiesthe location of the public key certificate to be presented to the serverat the time the SSL session is established. It is not required (but maybe provided) if the server does not require it. Some servers mayrequire it, some servers may request it but not require it, and someservers may not request it at all. It may be the same fileas the private key (combined key and certificate file) but this is notrecommended.
--sslkey <name>
	(Keyword: sslkey)Specifies the file name of the client side private SSL key. Some SSLencrypted servers may require client side keys and certificates forauthentication. In most cases, this is optional. This specifiesthe location of the private key used to sign transactions with the serverat the time the SSL session is established. It is not required (but maybe provided) if the server does not require it. Some servers mayrequire it, some servers may request it but not require it, and someservers may not request it at all. It may be the same fileas the public key (combined key and certificate file) but this is notrecommended. If a password is required to unlock the key, it will beprompted for at the time just prior to establishing the session to theserver. This can cause some complications in daemon mode.
--sslproto <name>
	(Keyword: sslproto)Forces an ssl protocol. Possible values are ‘ssl2’, ‘ssl3’ and‘tls1’. Try this if the default handshake does not work for your server.
--sslcertck
	(Keyword: sslcertck)Causes fetchmail to strictly check the server certificate against a set oflocal trusted certificates (see the sslcertpath option). If the servercertificate is not signed by one of the trusted ones (directly or indirectly),the SSL connection will fail. This checking should prevent man-in-the-middleattacks against the SSL connection. Note that CRLs are seemingly not currentlysupported by OpenSSL in certificate verification! Your system clock shouldbe reasonably accurate when using this option!
--sslcertpath <directory>
	(Keyword: sslcertpath)Sets the directory fetchmail uses to look up local certificates. The defaultis your OpenSSL default one. The directory must be hashed as OpenSSL expectsit - every time you add or modify a certificate in the directory, you needto use the c_rehash tool (which comes with OpenSSL in the tools/subdirectory).
--sslfingerprint
	(Keyword: sslfingerprint)Specify the fingerprint of the server key (an MD5 hash of the key) inhexadecimal notation with colons separating groups of two digits. The letterhex digits must be in upper case. This is the default format OpenSSL uses,and the one fetchmail uses to report the fingerprint when an SSL connectionis established. When this is specified, fetchmail will compare the server keyfingerprint with the given one, and the connection will fail if they do notmatch. This can be used to prevent man-in-the-middle attacks.

-S <hosts> | --smtphost <hosts>
	(Keyword: smtp[host])Specify a hunt list of hosts to forward mail to (one or morehostnames, comma-separated). Hosts are tried in list order; the firstone that is up becomes the forwarding target for the current run.Normally, ‘localhost’ is added to the end of the list as an invisibledefault. However, when using Kerberos authentication, the FQDN of themachine running fetchmail is added to the end of the list as aninvisible default. Each hostname may have a port number following thehost name. The port number is separated from the host name by aslash; the default port is 25 (or ‘‘smtp’’ under IPv6). If youspecify an absolute pathname (beginning with a /), it will beinterpreted as the name of a UNIX socket accepting LMTP connections(such as is supported by the Cyrus IMAP daemon) Example: --smtphost server1,server2/2525,server3,/var/imap/socket/lmtp This option can be used with ODMR, and will make fetchmail a relaybetween the ODMR server and SMTP or LMTP receiver.
--fetchdomains <hosts>
	(Keyword: fetchdomains)In ETRN or ODMR mode, this option specifies the list of domains theserver should ship mail for once the connection is turned around. Thedefault is the FQDN of the machine runningfetchmail.
-D <domain> | --smtpaddress <domain>
	(Keyword: smtpaddress) Specify the domain to be appended to addressesin RCPT TO lines shipped to SMTP. The name of the SMTP server (asspecified by --smtphost, or defaulted to "localhost") is used whenthis is not specified.
--smtpname <user@domain>
	(Keyword: smtpname)Specify the domain and user to be put in RCPT TO lines shipped to SMTP.The default user is the current local user.
-Z <nnn> | --antispam <nnn[, nnn]...>
	(Keyword: antispam)Specifies the list of numeric SMTP errors that are to be interpretedas a spam-block response from the listener. A value of -1 disablesthis option. For the command-line option, the list values shouldbe comma-separated.
-m <command> | --mda <command>
	(Keyword: mda) You can force mail to be passed to an MDA directly(rather than forwarded to port 25) with the --mda or -m option. Toavoid losing mail, use this option only with MDAs like procmail orsendmail that return a nonzero status on disk-full and otherresource-exhaustion errors; the nonzero status tells fetchmail thatdelivery failed and prevents the message from being deleted off theserver. If fetchmail is running as root, it sets its userid tothat of the target user while delivering mail through an MDA. Somepossible MDAs are "/usr/sbin/sendmail -i -f %F %T", "/usr/bin/deliver"and "/usr/bin/procmail -d %T" (but the latter is usually redundant asit’s what SMTP listeners normally forward to). Local deliveryaddresses will be inserted into the MDA command wherever you place a%T; the mail message’s From address will be inserted where you placean %F. In both cases the addresses are enclosed in single quotes (’),after removing any single quotes they may contain, before the MDAcommand is passed to the shell. Do not use an MDA invocationlike "sendmail -i -t" that dispatches on the contents of To/Cc/Bcc, itwill create mail loops and bring the just wrath of many postmastersdown upon your head. Also, do not try to combine multidropmode with an MDA such as procmail that can only accept one addressee;you will lose.
--lmtp	(Keyword: lmtp)Cause delivery via LMTP (Local Mail Transfer Protocol). A serviceport must be explicitly specified (with a slash suffix) on eachhost in the smtphost hunt list if this option is selected; thedefault port 25 will (in accordance with RFC 2033) not be accepted.
--bsmtp <filename>
	(keyword: bsmtp)Append fetched mail to a BSMTP file. This simply contains the SMTPcommands that would normally be generated by fetchmail when passingmail to an SMTP listener daemon. An argument of ‘-’ causes the mailto be written to standard output. Note that fetchmail’sreconstruction of MAIL FROM and RCPT TO lines is not guaranteedcorrect; the caveats discussed under THE USE AND ABUSE OF MULTIDROPMAILBOXES below apply.

-l <maxbytes> | --limit <maxbytes>
	(Keyword: limit) Takes a maximum octet size argument. Messages largerthan this size will not be fetched and will be left on the server (inforeground sessions, the progress messages will note that they are"oversized"). If the fetch protocol permits (in particular, underIMAP or POP3 without the fetchall option) the message will not bemarked seen An explicit --limit of 0 overrides any limits set in yourrun control file. This option is intended for those needing tostrictly control fetch time due to expensive and variable phone rates.Combined with --flush, it can be used to delete oversized messageswaiting on a server. In daemon mode, oversize notifications aremailed to the calling user (see the --warnings option). This optiondoes not work with ETRN or ODMR.
-w <interval> | --warnings <interval>
	(Keyword: warnings)Takes an interval in seconds. When you callfetchmail with a ‘limit’ option in daemon mode, this controls the interval atwhich warnings about oversized messages are mailed to the calling user(or the user specified by the ‘postmaster’ option). One suchnotification is always mailed at the end of the the first poll thatthe oversized message is detected. Thereafter, renotification issuppressed until after the warning interval elapses (it will takeplace at the end of the first following poll).
-b <count> | --batchlimit <count>
	(Keyword: batchlimit)Specify the maximum number of messages that will be shipped to an SMTPlistener before the connection is deliberately torn down and rebuilt(defaults to 0, meaning no limit). An explicit --batchlimit of 0overrides any limits set in your run control file. Whilesendmail(8) normally initiates delivery of a message immediatelyafter receiving the message terminator, some SMTP listeners are not soprompt. MTAs like smail(8) may wait till thedelivery socket is shut down to deliver. This may produce annoyingdelays when fetchmail is processing very large batches. Settingthe batch limit to some nonzero size will prevent these delays. Thisoption does not work with ETRN or ODMR.
-B <number> | --fetchlimit <number>
	(Keyword: fetchlimit)Limit the number of messages accepted from a given server in a singlepoll. By default there is no limit. An explicit --fetchlimit of 0overrides any limits set in your run control file.This option does not work with ETRN or ODMR.
--fetchsizelimit <number>
	(Keyword: fetchsizelimit)Limit the number of sizes of messages accepted from a given server ina single transaction. This option is useful in reducing the delay indownloading the first mail when there are too many mails in themailbox. By default, the limit is 100. If set to 0, sizes of allmessages are downloaded at the start.This option does not work with ETRN or ODMR. For POP3, the only validnon-zero value is 1.
--fastuidl <number>
	(Keyword: fastuidl)Do a binary instead of linear search for the first unseen UID. Binarysearch avoids downloading the UIDs of all mails. This saves time(especially in daemon mode) where downloading the same set of UIDs ineach poll is a waste of bandwidth. The number ‘n’ indicates how rarelya linear search should be done. In daemon mode, linear search is usedonce followed by binary searches in ‘n-1’ polls if ‘n’ is greater than1; binary search is always used if ‘n’ is 1; linear search is alwaysused if ‘n’ is 0. In non-daemon mode, binary search is used if ‘n’ is1; otherwise linear search is used.This option works with POP3 only.
-e <count> | --expunge <count>
	(keyword: expunge)Arrange for deletions to be made final after a given number ofmessages. Under POP2 or POP3, fetchmail cannot make deletions finalwithout sending QUIT and ending the session -- with this option on,fetchmail will break a long mail retrieval session into multiplesubsessions, sending QUIT after each sub-session. This is a gooddefense against line drops on POP3 servers that do not do theequivalent of a QUIT on hangup. Under IMAP,fetchmail normally issues an EXPUNGE command after each deletion in order toforce the deletion to be done immediately. This is safest when yourconnection to the server is flaky and expensive, as it avoidsresending duplicate mail after a line hit. However, on largemailboxes the overhead of re-indexing after every message can slam theserver pretty hard, so if your connection is reliable it is good to doexpunges less frequently. Also note that some servers enforce a delayof a few seconds after each quit, so fetchmail may not be able to getback in immediately after an expunge -- you may see "lock busy" errorsif this happens. If you specify this option to an integer N,it tellsfetchmail to only issue expunges on every Nth delete. An argument of zerosuppresses expunges entirely (so no expunges at all will be done untilthe end of run). This option does not work with ETRN or ODMR.

-u <name> | --username <name>
	(Keyword: user[name])Specifies the user identification to be used when logging in to the mailserver.The appropriate user identification is both server and user-dependent. The default is your login name on the client machine that is runningfetchmail. See USER AUTHENTICATION below for a complete description.
-I <specification> | --interface <specification>
	(Keyword: interface)Require that a specific interface device be up and have a specific localor remote IP address (or range) before polling. Frequentlyfetchmail is used over a transient point-to-point TCP/IP link established directlyto a mailserver via SLIP or PPP. That is a relatively secure channel.But when other TCP/IP routes to the mailserver exist (e.g. when the linkis connected to an alternate ISP), your username and password may bevulnerable to snooping (especially when daemon mode automatically pollsfor mail, shipping a clear password over the net at predictableintervals). The --interface option may be used to prevent this. Whenthe specified link is not up or is not connected to a matching IPaddress, polling will be skipped. The format is: interface/iii.iii.iii.iii/mmm.mmm.mmm.mmm The field before the first slash is the interface name (i.e. sl0, ppp0etc.). The field before the second slash is the acceptable IP address.The field after the second slash is a mask which specifies a range ofIP addresses to accept. If no mask is present 255.255.255.255 isassumed (i.e. an exact match). This option is currently only supportedunder Linux and FreeBSD. Please see themonitor section for below for FreeBSD specific information.
-M <interface> | --monitor <interface>
	(Keyword: monitor)Daemon mode can cause transient links which are automatically taken downafter a period of inactivity (e.g. PPP links) to remain upindefinitely. This option identifies a system TCP/IP interface to bemonitored for activity. After each poll interval, if the link is up butno other activity has occurred on the link, then the poll will beskipped. However, when fetchmail is woken up by a signal, themonitor check is skipped and the poll goes through unconditionally.This option is currently only supported under Linux and FreeBSD.For themonitor andinterface options to work for non root users under FreeBSD, the fetchmail binarymust be installed SGID kmem. This would be a security hole, butfetchmail runs with the effective GID set to that of the kmem grouponly when interface data is being collected.
--auth <type>
	(Keyword: auth[enticate])This option permits you to specify an authentication type (see USERAUTHENTICATION below for details). The possible values are any,‘password’, ‘kerberos_v5’ and ‘kerberos’ (or, forexcruciating exactness, ‘kerberos_v4’), gssapi,cram-md5, otp, ntlm, and ssh. When any (thedefault) is specified, fetchmail tries first methods that don’trequire a password (GSSAPI, KERBEROS_IV); then it looks for methodsthat mask your password (CRAM-MD5, X-OTP, NTLM); and only if the serverdoesn’t support any of those will it ship your password en clair.Other values may be used to force various authentication methods(ssh suppresses authentication). Any value other thanpassword, cram-md5, ntlm or otp suppresses fetchmail’snormal inquiry for a password. Specify ssh when you are usingan end-to-end secure connection such as an ssh tunnel; specifygssapi or kerberos_v4 if you are using a protocol variantthat employs GSSAPI or K4. Choosing KPOP protocol automaticallyselects Kerberos authentication. This option does not work with ETRN.

-f <pathname> | --fetchmailrc <pathname>
	Specify a non-default name for the~/.fetchmailrc run control file. The pathname argument must be either "-" (a singledash, meaning to read the configuration from standard input) or afilename. Unless the --version option is also on, a named fileargument must have permissions no more open than 0600 (u=rw,g=,o=) orelse be /dev/null.
-i <pathname> | --idfile <pathname>
	(Keyword: idfile)Specify an alternate name for the .fetchids file used to save POP3UIDs.
-n | --norewrite
	(Keyword: no rewrite)Normally,fetchmail edits RFC-822 address headers (To, From, Cc, Bcc, and Reply-To) infetched mail so that any mail IDs local to the server are expanded tofull addresses (@ and the mailserver hostname are appended). This enablesreplies on the client to get addressed correctly (otherwise yourmailer might think they should be addressed to local users on theclient machine!). This option disables the rewrite. (This option isprovided to pacify people who are paranoid about having an MTA editmail headers and want to know they can prevent it, but it is generallynot a good idea to actually turn off rewrite.)When using ETRN or ODMR, the rewrite option is ineffective.
-E <line> | --envelope <line>
	(Keyword: envelope)This option changes the headerfetchmail assumes will carry a copy of the mail’s envelope address. Normallythis is ‘X-Envelope-To’ but as this header is not standard, practicevaries. See the discussion of multidrop address handling below. As aspecial case, ‘envelope "Received"’ enables parsing of sendmail-styleReceived lines. This is the default, and it should not be necessaryunless you have globally disabled Received parsing with ‘no envelope’in the .fetchmailrc file.
-Q <prefix> | --qvirtual <prefix>
	(Keyword: qvirtual)The string prefix assigned to this option will be removed from the username found in the header specified with the envelope option(before doing multidrop name mapping or localdomain checking,if either is applicable). This option is useful if you are using fetchmail to collect the mail for an entire domain and your ISP (or your mailredirection provider) is using qmail.One of the basic features of qmail is the ‘Delivered-To:’ message header. Whenever qmail delivers a message to a local mailboxit puts the username and hostname of the envelope recipient on thisline. The major reason for this is to prevent mail loops. To set upqmail to batch mail for a disconnected site the ISP-mailhost will havenormally put that site in its ‘Virtualhosts’ control file so it willadd a prefix to all mail addresses for this site. This results in mailsent to ’username@userhost.userdom.dom.com’ having a‘Delivered-To:’ line of the form: Delivered-To: mbox-userstr-username@userhost.userdom.dom.com The ISP can make the ’mbox-userstr-’ prefix anything they choosebut a string matching the user host name is likely.By using the option ‘envelope Delivered-To:’ you can make fetchmail reliablyidentify the original envelope recipient, but you have to strip the‘mbox-userstr-’ prefix to deliver to the correct user.This is what this option is for.
--configdump
	Parse the~/.fetchmailrc file, interpret any command-line options specified, and dump aconfiguration report to standard output. The configuration report isa data structure assignment in the language Python. This optionis meant to be used with an interactive~/.fetchmailrc editor likefetchmailconf, written in Python.

All modes except ETRN require authentication of the client to the server.Normal user authentication infetchmail is very much like the authentication mechanism offtp(1).The correct user-id and password depend upon the underlying securitysystem at the mailserver.

If the mailserver is a Unix machine on which you have an ordinary useraccount, your regular login name and password are used withfetchmail. If you use the same login name on both the server and the client machines,you needn’t worry about specifying a user-id with the-u option -- the default behavior is to use your login name on theclient machine as the user-id on the server machine. If you use adifferent login name on the server machine, specify that login namewith the-u option. e.g. if your login name is ’jsmith’ on a machine named ’mailgrunt’,you would startfetchmail as follows:

	fetchmail -u jsmith mailgrunt

The default behavior offetchmail is to prompt you for your mailserver password before the connection isestablished. This is the safest way to usefetchmail and ensures that your password will not be compromised. You may also specifyyour password in your~/.fetchmailrc file. This is convenient when usingfetchmail in daemon mode or with scripts.

If you do not specify a password, andfetchmail cannot extract one from your~/.fetchmailrc file, it will look for a~/.netrc file in your home directory before requesting one interactively; if anentry matching the mailserver is found in that file, the password willbe used. Fetchmail first looks for a match on poll name; if it finds none,it checks for a match on via name. See theftp(1)man page for details of the syntax of the~/.netrc file. (This feature may allow you to avoid duplicating passwordinformation in more than one file.)

On mailservers that do not provide ordinary user accounts, your user-id andpassword are usually assigned by the server administrator when you apply fora mailbox on the server. Contact your server administrator if you don’t knowthe correct user-id and password for your mailbox account.

Early versions of POP3 (RFC1081, RFC1225) supported a crude form ofindependent authentication using therhosts file on the mailserver side. Under this RPOP variant, a fixedper-user ID equivalent to a password was sent in clear over a link toa reserved port, with the command RPOP rather than PASS to alert theserver that it should do special checking. RPOP is supportedbyfetchmail (you can specify ‘protocol RPOP’ to have the program send ‘RPOP’rather than ‘PASS’) but its use is strongly discouraged. Thisfacility was vulnerable to spoofing and was withdrawn in RFC1460.

RFC1460 introduced APOP authentication. In this variant of POP3,you register an APOP password on your server host (the programto do this with on the server is probably called popauth(8)). Youput the same password in your~/.fetchmailrc file. Each timefetchmail logs in, it sends a cryptographically secure hash of your password andthe server greeting time to the server, which can verify it bychecking its authorization database.

If your fetchmail was built with Kerberos support and you specifyKerberos authentication (either with --auth or the .fetchmailrcoption authenticate kerberos_v4) it will try to get a Kerberosticket from the mailserver at the start of each query. Note: ifeither the pollnane or via name is ‘hesiod’, fetchmail will try to useHesiod to look up the mailserver.

If you use POP3 or IMAP with GSSAPI authentication, fetchmail willexpect the server to have RFC1731- or RFC1734-conformant GSSAPIcapability, and will use it. Currently this has only been tested overKerberos V, so you’re expected to already have a ticket-grantingticket. You may pass a username different from your principal nameusing the standard --user command or by the .fetchmailrcoption user.

If your IMAP daemon returns the PREAUTH response in its greeting line,fetchmail will notice this and skip the normal authentication step.This can be useful, e.g. if you start imapd explicitly using ssh.In this case you can declare the authentication value ‘ssh’ on thatsite entry to stop .fetchmail from asking you for a passwordwhen it starts up.

If you are using POP3, and the server issues a one-time-passwordchallenge conforming to RFC1938, fetchmail will use yourpassword as a pass phrase to generate the required response. Thisavoids sending secrets over the net unencrypted.

Compuserve’s RPA authentication (similar to APOP) is supported. If youcompile in the support, fetchmail will try to perform an RPA pass-phraseauthentication instead of sending over the password en clair if itdetects "@compuserve.com" in the hostname.

If you are using IMAP, Microsoft’s NTLM authentication (used by MicrosoftExchange) is supported. If you compile in the support, fetchmailwill try to perform an NTLM authentication (instead of sending over thepassword en clair) whenever the server returns AUTH=NTLM in itscapability response. Specify a user option value that looks like‘user@domain’: the part to the left of the @ will be passed as theusername and the part to the right as the NTLM domain.

If you are using IPsec, the -T (--netsec) option can be used to passan IP security request to be used when outgoing IP connections areinitialized. You can also do this using the ‘netsec’ server optionin the .fetchmailrc file. In either case, the option value is astring in the format accepted by the net_security_strtorequest()function of the inet6_apps library.

You can access SSL encrypted services by specifying the --ssl option.You can also do this using the "ssl" server option in the .fetchmailrcfile. With SSL encryption enabled, queries are initiated over a connectionafter negotiating an SSL session. Some services, such as POP3 and IMAP,have different well known ports defined for the SSL encrypted services.The encrypted ports will be selected automatically when SSL is enabled andno explicit port is specified.

When connecting to an SSL encrypted server, the server presents a certificateto the client for validation. The certificate is checked to verify thatthe common name in the certificate matches the name of the server beingcontacted and that the effective and expiration dates in the certificateindicate that it is currently valid. If any of these checks fail, a warningmessage is printed, but the connection continues. The server certificatedoes not need to be signed by any specific Certifying Authority and maybe a "self-signed" certificate.

Some SSL encrypted servers may request a client side certificate. A clientside public SSL certificate and private SSL key may be specified. Ifrequested by the server, the client certificate is sent to the server forvalidation. Some servers may require a valid client certificate and mayrefuse connections if a certificate is not provided or if the certificateis not valid. Some servers may require client side certificates be signedby a recognized Certifying Authority. The format for the key files andthe certificate files is that required by the underlying SSL libraries(OpenSSL in the general case).

A word of care about the use of SSL: While above mentionedsetup with self-signed server certificates retrieved over the wirescan protect you from a passive eavesdropper it doesn’t help against anactive attacker. It’s clearly an improvement over sending thepasswords in clear but you should be aware that a man-in-the-middleattack is trivially possible (in particular with tools such as dsniff,http://www.monkey.org/~dugsong/dsniff/). Use of an ssh tunnel (seebelow for some examples) is preferable if you care seriously about thesecurity of your mailbox.

fetchmail also supports authentication to the ESMTP server on the client sideaccording to RFC 2554. You can specify a name/password pair to beused with the keywords ‘esmtpname’ and ‘esmtppassword’; the formerdefaults to the username of the calling user.

The--daemon <interval> or-d <interval> option runsfetchmail in daemon mode. You must specify a numeric argument which is apolling interval in seconds.

In daemon mode,fetchmail puts itself in background and runs forever, querying each specifiedhost and then sleeping for the given polling interval.

Simply invoking

	fetchmail -d 900

will, therefore, poll all the hosts described in your~/.fetchmailrc file (except those explicitly excluded with the ‘skip’ verb) onceevery fifteen minutes.

It is possible to set a polling intervalin your~/.fetchmailrc file by saying ‘set daemon <interval>’, where <interval> is aninteger number of seconds. If you do this, fetchmail will alwaysstart in daemon mode unless you override it with the command-lineoption --daemon 0 or -d0.

Only one daemon process is permitted per user; in daemon mode,fetchmail makes a per-user lockfile to guarantee this.

Normally, calling fetchmail with a daemon in the background sends awakeup signal to the daemon, forcing it to poll mailserversimmediately. (The wakeup signal is SIGHUP if fetchmail is running asroot, SIGUSR1 otherwise.) The wakeup action also clears any ‘wedged’flags indicating that connections have wedged due to failedauthentication or multiple timeouts.

The option--quit will kill a running daemon process instead of waking it up (if thereis no such process,fetchmail notifies you). If the --quit option is the only command-line option,that’s all there is to it.

The quit option may also be mixed with other command-line options; itseffect is to kill any running daemon before doing what the otheroptions specify in combination with the rc file.

The-L <filename> or--logfile <filename> option (keyword: set logfile) allows you to redirect status messagesemitted while detached into a specified logfile (follow theoption with the logfile name). The logfile is opened for append, soprevious messages aren’t deleted. This is primarily useful fordebugging configurations.

The--syslog option (keyword: set syslog) allows you to redirect status and errormessages emitted to thesyslog(3)system daemon if available.Messages are logged with an id of fetchmail, the facility LOG_MAIL,and priorities LOG_ERR, LOG_ALERT or LOG_INFO.This option is intended for logging status and error messages whichindicate the status of the daemon and the results while fetching mailfrom the server(s).Error messages for command line options and parsing the .fetchmailrcfile are still written to stderr, or to the specified log file.The--nosyslog option turns off use ofsyslog(3),assuming it’s turned on in the~/.fetchmailrc file, or that the-L or--logfile <file> option was used.

See Also

Retrieving Emails From Remote Servers With fetchmail on DebianFetchmail Mail Retrieval19.3.3. Fetchmail Red Hat Enterprise Linux 6 | Red Hat Customer Portalfetchmail - Unix, Linux Command

The-N or --nodetach option suppresses backgrounding and detachment of thedaemon process from its control terminal. This is primarily usefulfor debugging. Note that this also causes the logfile option to beignored (though perhaps it shouldn’t).

Note that while running in daemon mode polling a POP2 or IMAP2bis server,transient errors (such as DNS failures or sendmail delivery refusals)may force the fetchall option on for the duration of the next pollingcycle. This is a robustness feature. It means that if a message isfetched (and thus marked seen by the mailserver) but not deliveredlocally due to some transient error, it will be re-fetched during thenext poll cycle. (The IMAP logic doesn’t delete messages untilthey’re delivered, so this problem does not arise.)

If you touch or change the~/.fetchmailrc file while fetchmail is running in daemon mode, this will be detectedat the beginning of the next poll cycle. When a changed~/.fetchmailrc is detected, fetchmail rereads it and restarts from scratch (usingexec(2); no state information is retained in the new instance). Note alsothat if you break the~/.fetchmailrc file’s syntax, the new instance will softly and silently vanish awayon startup.

The--postmaster <name> option (keyword: set postmaster) specifies the last-resort username towhich multidrop mail is to be forwarded if no matching local recipientcan be found. Normally this is just the user who invokedfetchmail. If the invoking user is root, then the default of this option isthe user ‘postmaster’. Setting postmaster to the empty string causessuch mail to be discarded.

The--nobounce option suppresses the normal action of bouncing errors back to thesender in an RFC1894-conformant error message. If nobounce is on, themessage will go to the postmaster instead.

The--invisible option (keyword: set invisible) tries to make fetchmail invisible.Normally, fetchmail behaves like any other MTA would -- it generates aReceived header into each message describing its place in the chain oftransmission, and tells the MTA it forwards to that the mail came fromthe machine fetchmail itself is running on. If the invisible optionis on, the Received header is suppressed and fetchmail tries to spoofthe MTA it forwards to into thinking it came directly from themailserver host.

The--showdots option (keyword: set showdots) forces fetchmail to show progress dotseven if the current tty is not stdout (for example logfiles).Starting with fetchmail version 5.3.0,progress dots are only shown on stdout by default.

By specifying the--tracepolls option, you can ask fetchmail to add information to the Receivedheader on the form "polling {label} account {user}", where {label} isthe account label (from the specified rcfile, normally ~/.fetchmailrc)and {user} is the username which is used to log on to the mailserver. This header can be used to make filtering email where nouseful header information is available and you want mail fromdifferent accounts sorted into different mailboxes (this could, forexample, occur if you have an account on the same server running amailing list, and are subscribed to the list using that account). Thedefault is not adding any such header. In.fetchmailrc, this is called ‘tracepolls’.

The protocols fetchmail uses to talk to mailservers are next tobulletproof. In normal operation forwarding to port 25, no message isever deleted (or even marked for deletion) on the host until the SMTPlistener on the client side has acknowledged to fetchmail thatthe message has been either accepted for delivery or rejected due to aspam block.

When forwarding to an MDA, however, there is more possibilityof error. Some MDAs are ‘safe’ and reliably return a nonzero statuson any delivery error, even one due to temporary resource limits.The well-knownprocmail(1)program is like this; so are most programs designed as mail transportagents, such assendmail(1),andexim(1).These programs give back a reliable positive acknowledgement andcan be used with the mda option with no risk of mail loss. UnsafeMDAs, though, may return 0 even on delivery failure. If thishappens, you will lose mail.

The normal mode of fetchmail is to try to download only ‘new’messages, leaving untouched (and undeleted) messages you have alreadyread directly on the server (or fetched with a previous fetchmail--keep). But you may find that messages you’ve already read on theserver are being fetched (and deleted) even when you don’t specify--all. There are several reasons this can happen.

One could be that you’re using POP2. The POP2 protocol includes norepresentation of ‘new’ or ‘old’ state in messages, so fetchmailmust treat all messages as new all the time. But POP2 is obsolete, sothis is unlikely.

Under POP3, blame RFC1725. That version of the POP3 protocolspecification removed the LAST command, and some POP servers follow it(you can verify this by invoking fetchmail -v to the mailserverand watching the response to LAST early in the query). Thefetchmail code tries to compensate by using POP3’s UID feature,storing the identifiers of messages seen in each session until thenext session, in the .fetchids file. But this doesn’t trackmessages seen with other clients, or read directly with a mailer onthe host but not deleted afterward. A better solution would be toswitch to IMAP.

Another potential POP3 problem might be servers that insert messagesin the middle of mailboxes (some VMS implementations of mail arerumored to do this). The fetchmail code assumes that newmessages are appended to the end of the mailbox; when this is not trueit may treat some old messages as new and vice versa. The onlyreal fix for this problem is to switch to IMAP.

Yet another POP3 problem is that if they can’t make tempfiles in theuser’s home directory, some POP3 servers will hand back anundocumented response that causes fetchmail to spuriously report "Nomail".

The IMAP code uses the presence or absence of the server flag \Seento decide whether or not a message is new. Under Unix, it counts onyour IMAP server to notice the BSD-style Status flags set by mail useragents and set the \Seen flag from them when appropriate. All UnixIMAP servers we know of do this, though it’s not specified by the IMAPRFCs. If you ever trip over a server that doesn’t, the symptom willbe that messages you have already read on your host will look new tothe server. In this (unlikely) case, only messages you fetched withfetchmail --keep will be both undeleted and marked old.

In ETRN and ODMR modes, fetchmail does not actually retrieve messages;instead, it asks the server’s SMTP listener to start a queue flushto the client via SMTP. Therefore it sends only undelivered messages.

Many SMTP listeners allow administrators to set up ‘spam filters’ thatblock unsolicited email from specified domains. A MAIL FROM or DATA line thattriggers this feature will elicit an SMTP response which(unfortunately) varies according to the listener.

Newer versions ofsendmail return an error code of 571. This return valueis blessed by RFC1893 as "Delivery not authorized, message refused".

According to RFC2821, the correct thing to return in this situation is550 "Requested action not taken: mailbox unavailable" (the draft adds"[E.g., mailbox not found, no access, or command rejected for policyreasons].").

Older versions of theexim MTA return 501 "Syntax error in parameters or arguments".

Thepostfix MTA runs 554 as an antispam response.

Zmailer may reject code with a 500 response (followed by an enhanced statuscode that contains more information).

Return codes whichfetchmail treats as antispam responses and discardsthe message can be set with the ‘antispam’ option. This is one of theonly three circ*mstance under which fetchmail ever discards mail (the othersare the 552 and 553 errors described below, and the suppression ofmultidropped messages with a message-ID already seen).

Iffetchmail is fetching from an IMAP server, the antispam response will be detected andthe message rejected immediately after the headers have been fetched,without reading the message body. Thus, you won’t pay for downloadingspam message bodies.

By default, the list of antispam responses is empty.

If the spambounce option is on, mail that is spam-blockedtriggers an RFC1892 bounce message informing the originator that we donot accept mail from it.

Besides the spam-blocking described above, fetchmail takes specialactions on the following SMTP/ESMTP error responses

452 (insufficient system storage)
	Leave the message in the server mailbox for later retrieval.
552 (message exceeds fixed maximum message size)
	Delete the message from the server. Send bounce-mail to theoriginator.
553 (invalid sending domain)
	Delete the message from the server. Don’t even try to sendbounce-mail to the originator.

Other errors trigger bounce mail back to the originator.

The preferred way to set up fetchmail is to write a.fetchmailrc file in your home directory (you may do thisdirectly, with a text editor, or indirectly via fetchmailconf).When there is a conflict between the command-line arguments and thearguments in this file, the command-line arguments take precedence.

To protect the security of your passwords, when --version is not onyour ~/.fetchmailrc may not have more than 0600 (u=rw,g=,o=) permissions;fetchmail will complain and exit otherwise.

You may read the .fetchmailrc file as a list of commands tobe executed whenfetchmail is called with no arguments.

Comments begin with a ’#’ and extend through the end of the line.Otherwise the file consists of a series of server entries or globaloption statements in a free-format, token-oriented syntax.

There are four kinds of tokens: grammar keywords, numbers(i.e. decimal digit sequences), unquoted strings, and quoted strings.A quoted string is bounded by double quotes and may containwhitespace (and quoted digits are treated as a string). An unquotedstring is any whitespace-delimited token that is neither numeric, stringquoted nor contains the special characters ‘,’, ‘;’, ‘:’, or ‘=’.

Any amount of whitespace separates tokens in server entries, but isotherwise ignored. You may use standard C-style escapes (\n, \t,\b, octal, and hex) to embed non-printable characters or stringdelimiters in strings.

Each server entry consists of one of the keywords ‘poll’ or ‘skip’,followed by a server name, followed by server options, followed by anynumber of user descriptions. Note: the most common cause of syntaxerrors is mixing up user and server options.

For backward compatibility, the word ‘server’ is a synonym for ‘poll’.

You can use the noise keywords ‘and’, ‘with’,‘has’, ‘wants’, and ‘options’ anywhere in an entry to makeit resemble English. They’re ignored, but but can make entries mucheasier to read at a glance. The punctuation characters ’:’, ’;’ and’,’ are also ignored.

The ‘poll’ verb tells fetchmail to query this host when it is run withno arguments. The ‘skip’ verb tellsfetchmail not to poll this host unless it is explicitly named on the commandline. (The ‘skip’ verb allows you to experiment with test entriessafely, or easily disable entries for hosts that are temporarily down.)

Here are the legal options. Keyword suffixes enclosed insquare brackets are optional. Those corresponding to command-lineoptions are followed by ‘-’ and the appropriate option letter.

Here are the legal global options:

Keyword	Opt	Function
set daemon		Set a background poll interval in seconds
set postmaster		Give the name of the last-resort mail recipient
set no bouncemail		Direct error mail to postmaster rather than sender
set no spambounce		Send spam bounces
set logfile		Name of a file to dump error and status messages to
set idfile		Name of the file to store UID lists in
set syslog		Do error logging through syslog(3).
set no syslog		Turn off error logging through syslog(3).
set properties		String value is ignored by fetchmail (may be used by extension scripts)

Here are the legal server options:

Keyword	Opt	Function
via		Specify DNS name of mailserver, overriding poll name
proto[col]	-p	Specify protocol (case insensitive):POP2, POP3, IMAP, APOP, KPOP
local[domains]		Specify domain(s) to be regarded as local
port	-P	Specify TCP/IP service port
auth[enticate]		Set authentication type (default ‘any’)
timeout	-t	Server inactivity timeout in seconds (default 300)
envelope	-E	Specify envelope-address header name
no envelope		Disable looking for envelope address
qvirtual	-Q	Qmail virtual domain prefix to remove from user name
aka		Specify alternate DNS names of mailserver
interface	-I	specify IP interface(s) that must be up for server poll to take place
monitor	-M	Specify IP address to monitor for activity
plugin		Specify command through which to make server connections.
plugout		Specify command through which to make listener connections.
dns		Enable DNS lookup for multidrop (default)
no dns		Disable DNS lookup for multidrop
checkalias		Do comparison by IP address for multidrop
no checkalias		Do comparison by name for multidrop (default)
uidl	-U	Force POP3 to use client-side UIDLs
no uidl		Turn off POP3 use of client-side UIDLs (default)
interval		Only check this site every N poll cycles; N is a numeric argument.
tracepolls		Add poll tracing information to the Received header
netsec		Pass in IPsec security option request.
principal		Set Kerberos principal (only useful with imap and kerberos)
esmtpname		Set name for RFC2554 authentication to the ESMTP server.
esmtppassword		Set password for RFC2554 authentication to the ESMTP server.

Here are the legal user options:

See Also

fetchmail: fetch mail from a POP, IMAP, ETRN, or ODMR-capable server - Linux Manuals (1)

Keyword	Opt	Function
user[name]	-u	Set remote user name(local user name if name followed by ‘here’)
is		Connect local and remote user names
to		Connect local and remote user names
pass[word]		Specify remote account password
ssl		Connect to server over the specified base protocol using SSL encryption
sslcert		Specify file for client side public SSL certificate
sslkey		Specify file for client side private SSL key
sslproto		Force ssl protocol for connection
folder	-r	Specify remote folder to query
smtphost	-S	Specify smtp host(s) to forward to
fetchdomains		Specify domains for which mail should be fetched
smtpaddress	-D	Specify the domain to be put in RCPT TO lines
smtpname		Specify the user and domain to be put in RCPT TO lines
antispam	-Z	Specify what SMTP returns are interpreted as spam-policy blocks
mda	-m	Specify MDA for local delivery
bsmtp	-o	Specify BSMTP batch file to append to
preconnect		Command to be executed before each connection
postconnect		Command to be executed after each connection
keep	-k	Don’t delete seen messages from server
flush	-F	Flush all seen messages before querying
fetchall	-a	Fetch all messages whether seen or not
rewrite		Rewrite destination addresses for reply (default)
stripcr		Strip carriage returns from ends of lines
forcecr		Force carriage returns at ends of lines
pass8bits		Force BODY=8BITMIME to ESMTP listener
dropstatus		Strip Status and X-Mozilla-Status lines out of incoming mail
dropdelivered		Strip Delivered-To lines out of incoming mail
mimedecode		Convert quoted-printable to 8-bit in MIME messages
idle		Idle waiting for new messages after each poll (IMAP only)
no keep	-K	Delete seen messages from server (default)
no flush		Don’t flush all seen messages before querying (default)
no fetchall		Retrieve only new messages (default)
no rewrite		Don’t rewrite headers
no stripcr		Don’t strip carriage returns (default)
no forcecr		Don’t force carriage returns at EOL (default)
no pass8bits		Don’t force BODY=8BITMIME to ESMTP listener (default)
no dropstatus		Don’t drop Status headers (default)
no dropdelivered		Don’t drop Delivered-To headers (default)
no mimedecode		Don’t convert quoted-printable to 8-bit in MIME messages (default)
no idle		Don’t idle waiting for new messages after each poll (IMAP only)
limit	-l	Set message size limit
warnings	-w	Set message size warning interval
batchlimit	-b	Max # messages to forward in single connect
fetchlimit	-B	Max # messages to fetch in single connect
fetchsizelimit		Max # message sizes to fetch in single transaction
fastuidl		Use binary search for first unseen message (POP3 only)
expunge	-e	Perform an expunge on every #th message (IMAP and POP3 only)
properties		String value is ignored by fetchmail (may be used by extension scripts)

Remember that all user options must follow all server options.

In the .fetchmailrc file, the ‘envelope’ string argument may bepreceded by a whitespace-separated number. This number, if specified,is the number of such headers to skip (that is, an argument of 1selects the second header of the given type). This is sometime usefulfor ignoring bogus Received headers created by an ISP’s local deliveryagent.

The ‘folder’ and ‘smtphost’ options (unlike their command-lineequivalents) can take a space- or comma-separated list of namesfollowing them.

All options correspond to the obvious command-line arguments, exceptthe following: ‘via’, ‘interval’, ‘aka’, ‘is’, ‘to’, ‘dns’/‘no dns’,‘checkalias’/‘no checkalias’, ‘password’, ‘preconnect’, ‘postconnect’,‘localdomains’, ‘stripcr’/‘no stripcr’, ‘forcecr’/‘no forcecr’,‘pass8bits’/‘no pass8bits’ ‘dropstatus/no dropstatus’,‘dropdelivered/no dropdelivered’, ‘mimedecode/no mimedecode’, ‘idle/noidle’, and ‘no envelope’.

The ‘via’ option is for if you want to have morethan one configuration pointing at the same site. If it is present,the string argument will be taken as the actual DNS name of themailserver host to query.This will override the argument of poll, which can then simply be adistinct label for the configuration (e.g. what you would give on thecommand line to explicitly query this host).

The ‘interval’ option (which takes a numeric argument) allows you to poll aserver less frequently than the basic poll interval. If you say‘interval N’ the server this option is attached to will only bequeried every N poll intervals.

The ‘is’ or ‘to’ keywords associate the following local (client)name(s) (or server-name to client-name mappings separated by =) withthe mailserver user name in the entry. If an is/to list has ‘*’ asits last name, unrecognized names are simply passed through.

A single local name can be used to support redirecting your mail whenyour username on the client machine is different from your name on themailserver. When there is only a single local name, mail is forwardedto that local username regardless of the message’s Received, To, Cc,and Bcc headers. In this casefetchmail never does DNS lookups.

When there is more than one local name (or name mapping) thefetchmail code does look at the Received, To, Cc, and Bccheaders of retrieved mail (this is ‘multidrop mode’). It looks foraddresses with hostname parts that match your poll name or your ‘via’,‘aka’ or ‘localdomains’ options, and usually also for hostname partswhich DNS tells it are aliases of the mailserver. See the discussionof ‘dns’, ‘checkalias’, ‘localdomains’, and ‘aka’ for details on howmatching addresses are handled.

If fetchmail cannot match any mailserver usernames orlocaldomain addresses, the mail will be bounced.Normally it will be bounced to the sender, but if ‘nobounce’ is onit will go to the postmaster (which in turn defaults to being thecalling user).

The ‘dns’ option (normally on) controls the way addresses frommultidrop mailboxes are checked. On, it enables logic to check eachhost address that doesn’t match an ‘aka’ or ‘localdomains’ declarationby looking it up with DNS. When a mailserver username is recognizedattached to a matching hostname part, its local mapping is added tothe list of local recipients.

The ‘checkalias’ option (normally off) extends the lookups performedby the ‘dns’ keyword in multidrop mode, providing a way to cope withremote MTAs that identify themselves using their canonical name, whilethey’re polled using an alias.When such a server is polled, checks to extract the envelope addressfail, andfetchmail reverts to delivery using the To/Cc/Bcc headers (See below‘Header vs. Envelope addresses’).Specifying this option instructsfetchmail to retrieve all the IP addresses associated with both the poll nameand the name used by the remote MTA and to do a comparison of the IPaddresses. This comes in handy in situations where the remote serverundergoes frequent canonical name changes, that would otherwiserequire modifications to the rcfile. ‘checkalias’ has no effect if‘no dns’ is specified in the rcfile.

The ‘aka’ option is for use with multidrop mailboxes. It allows youto pre-declare a list of DNS aliases for a server. This is anoptimization hack that allows you to trade space for speed. Whenfetchmail, while processing a multidrop mailbox, grovels through message headerslooking for names of the mailserver, pre-declaring common ones cansave it from having to do DNS lookups. Note: the names you giveas arguments to ‘aka’ are matched as suffixes -- if you specify(say) ‘aka netaxs.com’, this will match not just a hostnamednetaxs.com, but any hostname that ends with ‘.netaxs.com’; such as(say) pop3.netaxs.com and mail.netaxs.com.

The ‘localdomains’ option allows you to declare a list of domainswhich fetchmail should consider local. When fetchmail is parsingaddress lines in multidrop modes, and a trailing segment of a hostname matches a declared local domain, that address is passed throughto the listener or MDA unaltered (local-name mappings are notapplied).

If you are using ‘localdomains’, you may also need to specify ‘noenvelope’, which disables fetchmail’s normal attempt to deducean envelope address from the Received line or X-Envelope-To header orwhatever header has been previously set by ‘envelope’. If you set ‘noenvelope’ in the defaults entry it is possible to undo that inindividual entries by using ‘envelope <string>’. As a special case,‘envelope "Received"’ restores the default parsing ofReceived lines.

The password option requires a string argument, which is the passwordto be used with the entry’s server.

The ‘preconnect’ keyword allows you to specify a shell command to beexecuted just before each timefetchmail establishes a mailserver connection. This may be useful if you areattempting to set up secure POP connections with the aid ofssh(1).If the command returns a nonzero status, the poll of that mailserverwill be aborted.

Similarly, the ‘postconnect’ keyword similarly allows you to specify ashell command to be executed just after each time a mailserverconnection is taken down.

The ‘forcecr’ option controls whether lines terminated by LF only aregiven CRLF termination before forwarding. Strictly speaking RFC821requires this, but few MTAs enforce the requirement it so this optionis normally off (only one such MTA, qmail, is in significant use attime of writing).

The ‘stripcr’ option controls whether carriage returns are strippedout of retrieved mail before it is forwarded. It is normally notnecessary to set this, because it defaults to ‘on’ (CR strippingenabled) when there is an MDA declared but ‘off’ (CR strippingdisabled) when forwarding is via SMTP. If ‘stripcr’ and ‘forcecr’ areboth on, ‘stripcr’ will override.

The ‘pass8bits’ option exists to cope with Microsoft mail programs thatstupidly slap a "Content-Transfer-Encoding: 7bit" on everything. Withthis option off (the default) and such a header present,fetchmail declares BODY=7BIT to an ESMTP-capable listener; this causes problems formessages actually using 8-bit ISO or KOI-8 character sets, which willbe garbled by having the high bits of all characters stripped. If‘pass8bits’ is on,fetchmail is forced to declare BODY=8BITMIME to any ESMTP-capable listener. Ifthe listener is 8-bit-clean (as all the major ones now are) the rightthing will probably result.

The ‘dropstatus’ option controls whether nonempty Status andX-Mozilla-Status lines are retained in fetched mail (the default) ordiscarded. Retaining them allows your MUA to see what messages (ifany) were marked seen on the server. On the other hand, it canconfuse some new-mail notifiers, which assume that anything with aStatus line in it has been seen. (Note: the empty Status linesinserted by some buggy POP servers are unconditionally discarded.)

The ‘dropdelivered’ option controls wether Delivered-To headers willbe kept in fetched mail (the default) or discarded. These headers areadded by Qmail and Postfix mailservers in order to avoid mail loops butmay get in your way if you try to "mirror" a mailserver within the samedomain. Use with caution.

The ‘mimedecode’ option controls whether MIME messages using thequoted-printable encoding are automatically converted into pure 8-bitdata. If you are delivering mail to an ESMTP-capable, 8-bit-cleanlistener (that includes all of the major MTAs like sendmail), thenthis will automatically convert quoted-printable message headers anddata into 8-bit data, making it easier to understand when readingmail. If your e-mail programs know how to deal with MIME messages,then this option is not needed. The mimedecode option is off bydefault, because doing RFC2047 conversion on headers throws awaycharacter-set information and can lead to bad results if the encodingof the headers differs from the body encoding.

The ‘idle’ option is intended to be used with IMAP servers supportingthe RFC2177 IDLE command extension, but does not strictly require it.If it is enabled, and fetchmail detects that IDLE is supported, anIDLE will be issued at the end of each poll. This will tell the IMAPserver to hold the connection open and notify the client when new mailis available. If IDLE is not supported, fetchmail will simulate it byperiodically issuing NOOP. If you need to poll a link frequently, IDLEcan save bandwidth by eliminating TCP/IP connects and LOGIN/LOGOUTsequences. On the other hand, an IDLE connection will eat almost allof your fetchmail’s time, because it will never drop the connectionand allow other pools to occur unless the server times out the IDLE.It also doesn’t work with multiple folders; only the first folder willever be polled.

The ‘properties’ option is an extension mechanism. It takes a stringargument, which is ignored by fetchmail itself. The string argument may beused to store configuration information for scripts which require it.In particular, the output of ‘--configdump’ option will make propertiesassociated with a user entry readily available to a Python script.

The words ‘here’ and ‘there’ have useful English-likesignificance. Normally ‘user eric is esr’ would mean thatmail for the remote user ‘eric’ is to be delivered to ‘esr’,but you can make this clearer by saying ‘user eric there is esr here’,or reverse it by saying ‘user esr here is eric there’

Legal protocol identifiers for use with the ‘protocol’ keyword are:

 auto (or AUTO) pop2 (or POP2) pop3 (or POP3) sdps (or SDPS) imap (or IMAP) apop (or APOP) kpop (or KPOP)

Legal authentication types are ‘any’, ‘password’, ‘kerberos’, ’kereberos_v5’and ‘gssapi’, ‘cram-md5’, ‘otp’, ‘ntlm’, ‘ssh‘.The ‘password’ type specifies authentication by normal transmission of apassword (the password may be plaintext or subject toprotocol-specific encryption as in APOP); ‘kerberos’ tellsfetchmail to try to get a Kerberos ticket at the start of eachquery instead, and send an arbitrary string as the password; and‘gssapi’ tells fetchmail to use GSSAPI authentication. See the descriptionof the ‘auth’ keyword for more.

Specifying ‘kpop’ sets POP3 protocol over port 1109 with Kerberos V4authentication. These defaults may be overridden by later options.

There are currently four global option statements; ‘set logfile’followed by a string sets the same global specified by --logfile. Acommand-line --logfile option will override this. Also, ‘set daemon’sets the poll interval as --daemon does. This can be overridden by acommand-line --daemon option; in particular --daemon 0 can be used toforce foreground operation. The ‘set postmaster’ statement sets theaddress to which multidrop mail defaults if there are no localmatches. Finally, ‘set syslog’ sends log messages to syslogd(8).

When trying to determine the originating address of a message,fetchmail looks through headers in the following order:

 Return-Path: Resent-Sender: (ignored if it doesn’t contain an @ or !) Sender: (ignored if it doesn’t contain an @ or !) Resent-From: From: Reply-To: Apparently-From:

The originating address is used for logging, and to set the MAIL FROMaddress when forwarding to SMTP. This order is intended to copegracefully with receiving mailing list messages in multidrop mode. Theintent is that if a local address doesn’t exist, the bounce messagewon’t be returned blindly to the author or to the list itself, butrather to the list manager (which is less annoying).

In multidrop mode, destination headers are processed as follows:First, fetchmail looks for the Received: header (or whichever one isspecified by the ‘envelope’ option) to determine the localrecipient address. If the mail is addressed to more than one recipient,the Received line won’t contain any information regarding recipient addresses.

Then fetchmail looks for the Resent-To:, Resent-Cc:, and Resent-Bcc:lines. If they exists, they should contain the final recipients andhave precedence over their To:/Cc:/Bcc: counterparts. If the Resent-*lines doesn’t exist, the To:, Cc:, Bcc: and Apparently-To: lines arelooked for. (The presence of a Resent-To: is taken to imply that theperson referred by the To: address has already received the originalcopy of the mail).

Note that although there are password declarations in a good manyof the examples below, this is mainly for illustrative purposes.We recommend stashing account/password pairs in your $HOME/.netrcfile, where they can be used not just by fetchmail but by ftp(1) andother programs.

Basic format is:

 poll SERVERNAME protocol PROTOCOL username NAME password PASSWORD

Example:

 poll pop.provider.net protocol pop3 username "jsmith" password "secret1"

Or, using some abbreviations:

 poll pop.provider.net proto pop3 user "jsmith" password "secret1"

Multiple servers may be listed:

 poll pop.provider.net proto pop3 user "jsmith" pass "secret1" poll other.provider.net proto pop2 user "John.Smith" pass "My^Hat"

Here’s a version of those two with more whitespace and some noise words:

 poll pop.provider.net proto pop3 user "jsmith", with password secret1, is "jsmith" here; poll other.provider.net proto pop2: user "John.Smith", with password "My^Hat", is "John.Smith" here;

This version is much easier to read and doesn’t cost significantlymore (parsing is done only once, at startup time).

If you need to include whitespace in a parameter string, enclose thestring in double quotes. Thus:

 poll mail.provider.net with proto pop3: user "jsmith" there has password "u can’t krak this" is jws here and wants mda "/bin/mail"

You may have an initial server description headed by the keyword‘defaults’ instead of ‘poll’ followed by a name. Such a recordis interpreted as defaults for all queries to use. It may be overwrittenby individual server descriptions. So, you could write:

 defaults proto pop3 user "jsmith" poll pop.provider.net pass "secret1" poll mail.provider.net user "jjsmith" there has password "secret2"

It’s possible to specify more than one user per server (this is onlylikely to be useful when running fetchmail in daemon mode as root).The ‘user’ keyword leads off a user description, and every user specificationin a multi-user entry must include it. Here’s an example:

 poll pop.provider.net proto pop3 port 3111 user "jsmith" with pass "secret1" is "smith" here user jones with pass "secret2" is "jjones" here keep

This associates the local username ‘smith’ with the pop.provider.netusername ‘jsmith’ and the local username ‘jjones’ with thepop.provider.net username ‘jones’. Mail for ‘jones’ is kept on theserver after download.

Here’s what a simple retrieval configuration for a multi-drop mailboxlooks like:

 poll pop.provider.net: user maildrop with pass secret1 to golux ’hurkle’=’happy’ snark here

This says that the mailbox of account ‘maildrop’ on the server is amulti-drop box, and that messages in it should be parsed for theserver user names ‘golux’, ‘hurkle’, and ‘snark’. It furtherspecifies that ‘golux’ and ‘snark’ have the same name on theclient as on the server, but mail for server user ‘hurkle’ should bedelivered to client user ‘happy’.

Here’s an example of another kind of multidrop connection:

 poll pop.provider.net localdomains loonytoons.org toons.org: user maildrop with pass secret1 to * here

This also says that the mailbox of account ‘maildrop’ on the server isa multi-drop box. It tells fetchmail that any address in theloonytoons.org or toons.org domains (including subdomain addresses like‘joe@daffy.loonytoons.org’) should be passed through to the local SMTPlistener without modification. Be careful of mail loops if you do this!

Here’s an example configuration using ssh and the plugin option. Thequeries are made directly on the stdin and stdout of imapd via ssh.Note that in this setup, IMAP authentication can be skipped.

poll mailhost.net with proto imap: plugin "ssh %h /usr/sbin/imapd" auth ssh;user esr is esr here

Use the multiple-local-recipients feature with caution -- it can bite.All multidrop features are ineffective in ETRN and ODMR modes.

Also, note that in multidrop mode duplicate mails are suppressed. Apiece of mail is considered duplicate if it has the same message-ID asthe message immediately preceding and more than one addressee. Suchruns of messages may be generated when copies of a message addressedto multiple users are delivered to a multidrop box.

The fundamental problem is that by having your mailserver toss severalpeoples’ mail in a single maildrop box, you may have thrown awaypotentially vital information about who each piece of mail wasactually addressed to (the ‘envelope address’, as opposed to theheader addresses in the RFC822 To/Cc/Bcc headers). This ‘envelopeaddress’ is the address you need in order to reroute mail properly.

Sometimesfetchmail can deduce the envelope address. If the mailserver MTA issendmail and the item of mail had just one recipient, the MTA will have writtena ‘by/for’ clause that gives the envelope addressee into its Receivedheader. But this doesn’t work reliably for other MTAs, nor if there ismore than one recipient. By default, fetchmail looks forenvelope addresses in these lines; you can restore this default with-E "Received" or ‘envelope Received’.

Alternatively, some SMTP listeners and/or mail servers insert a headerin each message containing a copy of the envelope addresses. Thisheader (when it exists) is often ‘X-Envelope-To’. Fetchmail’sassumption about this can be changed with the -E or ‘envelope’ option.Note that writing an envelope header of this kind exposes the names ofrecipients (including blind-copy recipients) to all receivers of themessages; it is therefore regarded by some administrators as asecurity/privacy problem.

A slight variation of the ‘X-Envelope-To’ header is the ‘Delivered-To’ putby qmail to avoid mail loops. It will probably prefix the user name with astring that normally matches the user’s domain. To remove this prefix youcan use the -Q or ‘qvirtual’ option.

Sometimes, unfortunately, neither of these methods works. When theyall fail, fetchmail must fall back on the contents of To/Cc/Bccheaders to try to determine recipient addressees -- and these are notreliable. In particular, mailing-list software often ships mail withonly the list broadcast address in the To header.

Whenfetchmail cannot deduce a recipient address that is local, and the intendedrecipient address was anyone other than fetchmail’s invoking user,mail will get lost. This is what makes the multidrop feature risky.

A related problem is that when you blind-copy a mail message, the Bccinformation is carried only as envelope address (it’s not putin the headers fetchmail can see unless there is an X-Envelopeheader). Thus, blind-copying to someone who gets mail over afetchmail link will fail unless the the mailserver host routinelywrites X-Envelope or an equivalent header into messages in your maildrop.

Multiple local names can be used to administer a mailing list from theclient side of a fetchmail collection. Suppose your name is‘esr’, and you want to both pick up your own mail and maintain a mailinglist called (say) "fetchmail-friends", and you want to keep the aliaslist on your client machine.

On your server, you can alias ‘fetchmail-friends’ to ‘esr’; then, inyour .fetchmailrc, declare ‘to esr fetchmail-friends here’.Then, when mail including ‘fetchmail-friends’ as a local addressgets fetched, the list name will be appended to the list ofrecipients your SMTP listener sees. Therefore it will undergo aliasexpansion locally. Be sure to include ‘esr’ in the local aliasexpansion of fetchmail-friends, or you’ll never see mail sent only tothe list. Also be sure that your listener has the "me-too" option set(sendmail’s -oXm command-line option or OXm declaration) so your nameisn’t removed from alias expansions in messages you send.

This trick is not without its problems, however. You’ll begin to seethis when a message comes in that is addressed only to a mailing listyou do not have declared as a local name. Each such messagewill feature an ‘X-Fetchmail-Warning’ header which is generatedbecause fetchmail cannot find a valid local name in the recipientaddresses. Such messages default (as was described above) to beingsent to the local user runningfetchmail, but the program has no way to know that that’s actually the right thing.

Multidrop mailboxes andfetchmail serving multiple users in daemon mode do not mix. The problem, again, ismail from mailing lists, which typically does not have an individualrecipient address on it. Unlessfetchmail can deduce an envelope address, such mail will only go to the accountrunning fetchmail (probably root). Also, blind-copied users are verylikely never to see their mail at all.

If you’re tempted to usefetchmail to retrieve mail for multiple users from a single mail drop via POP orIMAP, think again (and reread the section on header and envelopeaddresses above). It would be smarter to just let the mail sit in themailserver’s queue and use fetchmail’s ETRN or ODMR modes to triggerSMTP sends periodically (of course, this means you have to poll morefrequently than the mailserver’s expiry period). If you can’t arrangethis, try setting up a UUCP feed.

If you absolutely must use multidrop for this purpose, make sureyour mailserver writes an envelope-address header that fetchmail cansee. Otherwise you will lose mail and it will come backto haunt you.

Normally, when multiple users are declaredfetchmail extracts recipient addresses as described above and checks each hostpart with DNS to see if it’s an alias of the mailserver. If so, thename mappings described in the to ... here declaration are done andthe mail locally delivered.

This is the safest but also slowest method. To speed it up,pre-declare mailserver aliases with ‘aka’; these are checked beforeDNS lookups are done. If you’re certain your aka list containsall DNS aliases of the mailserver (and all MX names pointing at it)you can declare ‘no dns’ to suppress DNS lookups entirely andonly match against the aka list.

To facilitate the use offetchmail in shell scripts, an exit code is returned to give an indicationof what occurred during a given connection.

The exit codes returned byfetchmail are as follows:

0	One or more messages were successfully retrieved (or, if the -c optionwas selected, were found waiting but not retrieved).
1	There was no mail awaiting retrieval. (There may have been old mail stillon the server but not selected for retrieval.)
2	An error was encountered when attempting to open a socket to retrievemail. If you don’t know what a socket is, don’t worry about it --just treat this as an ’unrecoverable error’. This error can also bebecause a protocol fetchmail wants to use is not listed in /etc/services.
3	The user authentication step failed. This usually means that a baduser-id, password, or APOP id was specified. Or it may mean that youtried to run fetchmail under circ*mstances where it did not havestandard input attached to a terminal and could not prompt for amissing password.
4	Some sort of fatal protocol error was detected.
5	There was a syntax error in the arguments tofetchmail.
6	The run control file had bad permissions.
7	There was an error condition reported by the server. Can alsofire iffetchmail timed out while waiting for the server.
8	Client-side exclusion error. This meansfetchmail either found another copy of itself already running, or failed in sucha way that it isn’t sure whether another copy is running.
9	The user authentication step failed because the server responded "lockbusy". Try again after a brief pause! This error is not implementedfor all protocols, nor for all servers. If not implemented for yourserver, "3" will be returned instead, see above. May be returned whentalking to qpopper or other servers that can respond with "lock busy"or some similar text containing the word "lock".
10	Thefetchmail run failed while trying to do an SMTP port open or transaction.
11	Fatal DNS error. Fetchmail encountered an error while performinga DNS lookup at startup and could not proceed.
12	BSMTP batch file could not be opened.
13	Poll terminated by a fetch limit (see the --fetchlimit option).
14	Server busy indication.
15	Server timed out during an IMAP IDLE.
23	Internal error. You should see a message on standard error withdetails.

Whenfetchmail queries more than one host, return status is 0 if any querysuccessfully retrieved mail. Otherwise the returned error status isthat of the last host queried.

~/.fetchmailrc
	default run control file
~/.fetchids
	default location of file associating hosts with last message IDs seen(used only with newer RFC1725-compliant POP3 servers supporting theUIDL command).
~/.fetchmail.pid
	lock file to help prevent concurrent runs (non-root mode).
~/.netrc
	your FTP run control file, which (if present) will be searched forpasswords as a last resort before prompting for one interactively.
/var/run/fetchmail.pid
	lock file to help prevent concurrent runs (root mode, Linux systems).
/etc/fetchmail.pid
	lock file to help prevent concurrent runs (root mode, systems without /var/run).

If the FETCHMAILUSER variable is set, it is used as the name of thecalling user (default local name) for purposes such as mailing errornotifications. Otherwise, if either the LOGNAME or USER variable iscorrectly set (e.g. the corresponding UID matches the session user ID)then that name is used as the default local name. Otherwisegetpwuid(3) must be able to retrieve a password entry for thesession ID (this elaborate logic is designed to handle the case ofmultiple names per userid gracefully).

If the environment variable FETCHMAILHOME is set to a valid andexisting directory name, the .fetchmailrc and .fetchids and.fetchmail.pid files are put there instead of in the invoking user’shome directory (and lose the leading dots on their names). The.netrc file is looked for in the the invoking user’s home directoryregardless of FETCHMAILHOME’s setting.

If afetchmail daemon is running as root, SIGHUP wakes it up from its sleep phase andforces a poll of all non-skipped servers (this is in accordance withthe usual conventions for system daemons).

Iffetchmail is running in daemon mode as non-root, use SIGUSR1 to wake it (this isso SIGHUP due to logout can retain the default action of killing it).

Runningfetchmail in foreground while a background fetchmail is running will dowhichever of these is appropriate to wake it up.

The mda and plugin options interact badly. In order to collect errorstatus from the MDA, fetchmail has to change its normal signalhandling so that dead plugin processes don’t get reaped until the endof the poll cycle. This can cause resource starvation if too manyzombies accumulate. So either don’t deliver to a MDA using plugins orrisk being overrun by an army of undead.

The RFC822 address parser used in multidrop mode chokes on some@-addresses that are technically legal but bizarre. Strange uses ofquoting and embedded comments are likely to confuse it.

In a message with multiple envelope headers, only the last oneprocessed will be visible to fetchmail. To get around this, use amailserver-side filter that consolidates the contents of all envelopeheaders into a single one (procmail, mailagent, or maildrop can beprogrammed to do this fairly easily).

Use of some of these protocols requires that the program sendunencrypted passwords over the TCP/IP connection to the mailserver.This creates a risk that name/password pairs might be snaffled with apacket sniffer or more sophisticated monitoring software. Under Linuxand FreeBSD, the --interface option can be used to restrict polling toavailability of a specific interface device with a specific local orremote IP address, but snooping is still possible if (a) either hosthas a network device that can be opened in promiscuous mode, or (b)the intervening network link can be tapped. We recommend the use ofssh(1)tunnelling to not only shroud your passwords but encrypt the entireconversation.

Use of the %F or %T escapes in an mda option could open a securityhole, because they pass text manipulable by an attacker to a shellcommand. Potential shell characters are replaced by ‘_’ beforeexecution. The hole is further reduced by the fact that fetchmailtemporarily discards any suid privileges it may have while running theMDA. For maximum safety, however, don’t use an mda command containing%F or %T when fetchmail is run from the root account itself.

Fetchmail’s method of sending bouncemail and spam bounces requires thatport 25 of localhost be available for sending mail via SMTP.

If you modify a~/.fetchmailrc while a background instance is running and break the syntax, thebackground instance will die silently. Unfortunately, it can’tdie noisily because we don’t yet know whether syslog should be enabled.On some systems, fetchmail dies quietly even if there is no syntaxerror; this seems to have something to do with buggy terminal ioctlcode in the kernel.

The -f - option (reading a configuration from stdin) is incompatiblewith the plugin option.

The UIDL code is generally flaky and tends to lose its state on errorsand line drops (so that old messages are re-seen). If this happens toyou, switch to IMAP4.

The ‘principal’ option only handles Kerberos IV, not V.

Send comments, bug reports, gripes, and the like to thefetchmail-friends list <fetchmail-friends@lists.ccil.org>. An HTML FAQ isavailable at the fetchmail home page; surf tohttp://www.catb.org/~esr/fetchmail or do a WWW search for pages with‘fetchmail’ in their titles.

Eric S. Raymond <esr@snark.thyrsus.com>. Too many other people toname here have contributed code and patches.This program is descended from and replacespopclient, by Carl Harris <ceharris@mal.com>; the internals have become quite different,but some of its interface design is directly traceable to thatancestral program.

mutt(1), elm(1), mail(1), sendmail(8), popd(8), imapd(8), netrc(5)

SMTP/ESMTP:
	RFC 821, RFC2821, RFC 1869, RFC 1652, RFC 1870, RFC 1983, RFC 1985,RFC 2554.
mail:	RFC 822, RFC2822, RFC 1123, RFC 1892, RFC 1894.
POP2:	RFC 937
POP3:	RFC 1081, RFC 1225, RFC 1460, RFC 1725, RFC1734, RFC 1939, RFC 1957,RFC2195, RFC 2449.
APOP:	RFC 1460, RFC 1725, RFC 1939.
RPOP:	RFC 1081, RFC 1225.
IMAP2/IMAP2BIS:
	RFC 1176, RFC 1732.
IMAP4/IMAP4rev1:
	RFC 1730, RFC 1731, RFC 1732, RFC 2060, RFC 2061, RFC 2195, RFC 2177,RFC 2683.
ETRN:	RFC 1985.
ODMR/ATRN:
	RFC 2645.
OTP:	RFC 1938.
LMTP:	RFC 2033.
GSSAPI:
	RFC 1508.
TLS	RFC 2595.