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Linux / Unix Command: fetchmail
Command Library

NAME

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

 

SYNOPSIS

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

 

DESCRIPTION

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

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

While fetchmail is primarily intended to be used over on-demand TCP/IP links (such as SLIP or PPP connections), it may also be useful as a message transfer agent 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 to port 25 on the machine it is running on (localhost), just as though it were being passed in over a normal TCP/IP link. The mail will then be delivered locally via your system's MDA (Mail Delivery Agent, usually sendmail(8) but your system may use a different one such as smail, mmdf, exim, or qmail). All the delivery-control mechanisms (such as .forward files) normally available through your system MDA and local delivery agents will therefore work.

If no port 25 listener is available, but your fetchmail configuration was told about a reliable local MDA, it will use that MDA for local delivery instead. At build time, fetchmail normally looks for executable procmail(1) and sendmail(1) binaries.

If the program fetchmailconf is available, it will assist you in setting up and editing a fetchmailrc configuration. It runs under X and requires that the language Python and the Tk toolkit be present on your system. If you are first setting up fetchmail for single-user mode, it is recommended that you use Novice mode. Expert mode provides complete control of fetchmail configuration, including the multidrop features. In either case, the `Autoprobe' button will tell you the most capable protocol a given mailserver supports, and warn you of potential problems with that server.

 

GENERAL OPERATION

The behavior of fetchmail 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 what the fetchmailconf program edits). Command-line options override ~/.fetchmailrc declarations.

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

To facilitate the use of fetchmail in scripts and pipelines, it returns an appropriate exit code upon termination -- see EXIT CODES below.

The following options modify the behavior of fetchmail. It is seldom necessary to specify any of these once you have a working .fetchmailrc file set up.

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

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

General Options

-V | --version
Displays the version information for your copy of fetchmail. No mail fetch is performed. Instead, for each server specified, all the option information that would be computed if fetchmail were connecting to that server is displayed. Any non-printables in passwords or other string names are shown as backslashed C-like escape sequences. This option is useful for verifying that your options 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). It doesn't play well with queries to multiple sites, and doesn't work with ETRN or ODMR. It will return a false positive if you leave read but undeleted mail in your server mailbox and your fetch protocol can't tell 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 are normally echoed to standard error during a fetch (but does not suppress actual error messages). The --verbose option overrides this.
-v | --verbose
Verbose mode. All control messages passed between fetchmail and the mailserver are echoed to stdout. Overrides --silent. Doubling this option (-v -v) causes extra diagnostic information to be printed.
 

Disposal Options

-a | --all
(Keyword: fetchall) Retrieve both old (seen) and new messages from the mailserver. The default 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 (see RETRIEVAL FAILURE MODES below) and this option does not work with ETRN or ODMR.
-k | --keep
(Keyword: keep) Keep retrieved messages on the remote mailserver. Normally, messages are deleted from the folder on the mailserver after they have been retrieved. Specifying the keep option causes retrieved messages to remain in your folder on the mailserver. This option does not work with ETRN or ODMR.
-K | --nokeep
(Keyword: nokeep) Delete retrieved messages from the remote mailserver. This option forces retrieved mail to be deleted. It may be useful if you 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 the mailserver before retrieving new messages. This option does not work with ETRN or ODMR. Warning: if your local MTA hangs and fetchmail is aborted, the next time you run fetchmail, it will delete mail that was never delivered to you. What you probably want is the default setting: if you don't specify `-k', then fetchmail will automatically delete messages after successful delivery.
 

Protocol and Query Options

-p <proto> | --protocol <proto>
(Keyword: proto[col]) Specify the protocol to use when communicating with the remote mailserver. 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 support has 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 (communicating with standard server daemons to fetch mail already delivered to a mailbox on the server) except ETRN and ODMR. The ETRN mode allows you to ask a compliant ESMTP server (such as BSD sendmail at release 8.8.0 or higher) to immediately open a sender-SMTP connection to your client machine and begin forwarding any items addressed to your client machine in the server's queue of undelivered mail. The ODMR mode requires an ODMR-capable server and works similarly to ETRN, except that it does not require the client machine to have a static DNS.
-U | --uidl
(Keyword: uidl) Force UIDL use (effective only with POP3). Force client-side tracking of `newness' of messages (UIDL stands for ``unique ID listing'' and is described in RFC1725). Use with `keep' to use a mailbox as a baby news drop for a group of users. The fact that seen messages are skipped is logged, unless error logging is done through syslog while running in daemon 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 have well-established default port numbers.
--principal <principal>
(Keyword: principal) The principal option permits you to specify a service principal for mutual authentication. This is applicable to POP3 or IMAP with Kerberos authentication.
-t <seconds> | --timeout <seconds>
(Keyword: timeout) The timeout option allows you to set a server-nonresponse timeout in seconds. If a mailserver does not send a greeting message or respond to commands for the given number of seconds, fetchmail will hang up on it. Without such a timeout fetchmail might hang up indefinitely trying to fetch mail from a down host. This would be particularly annoying for a fetchmail running in background. There is a default timeout which fetchmail -V will report. If a given connection receives too many timeouts in succession, 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 external program to establish the TCP connection. This is useful if you want to use socks, SSL, ssh, or need some special firewalling setup. The program will be looked up in $PATH and can optionally be passed the hostname and port as arguments using "%h" and "%p" respectively (note that the interpolation logic is rather primitive, and these token must be bounded by whitespace or beginning of string or end of string). Fetchmail will write to the plugin's stdin and read from the plugin's stdout.
--plugout <command>
(Keyword: plugout) Identical to the plugin option above, but this one is used for the SMTP connections (which will probably not need it, so it has been separated from plugin).
-r <name> | --folder <name>
(Keyword: folder[s]) Causes a specified non-default mail folder on the mailserver (or comma-separated list of folders) to be retrieved. The syntax of the folder name is server-dependent. This option is not available under POP3, ETRN, or ODMR.
--tracepolls
(Keyword: tracepolls) Tell fetchail to poll trace information in the form `polling %s account %s' to the Received line it generates, where the %s parts are replaced by the user's remote name and the poll label (the Received header also normally includes the server's truename). This can be used to facilate mail filtering based on the account it is being received from.
--ssl
(Keyword: ssl) Causes the connection to the mail server to be encrypted via SSL. Connect to the server using the specified base protocol over a connection secured by SSL. SSL support must be present at the server. If no port is specified, the connection is attempted to the well known port of the SSL version of the base protocol. This is generally a different port than the port used by the base protocol. For IMAP, this is port 143 for the clear protocol and port 993 for the SSL secured protocol.
--sslcert <name>
(Keyword: sslcert) Specifies the file name of the client side public SSL certificate. Some SSL encrypted servers may require client side keys and certificates for authentication. In most cases, this is optional. This specifies the location of the public key certificate to be presented to the server at the time the SSL session is established. It is not required (but may be provided) if the server does not require it. Some servers may require it, some servers may request it but not require it, and some servers may not request it at all. It may be the same file as the private key (combined key and certificate file) but this is not recommended.
--sslkey <name>
(Keyword: sslkey) Specifies the file name of the client side private SSL key. Some SSL encrypted servers may require client side keys and certificates for authentication. In most cases, this is optional. This specifies the location of the private key used to sign transactions with the server at the time the SSL session is established. It is not required (but may be provided) if the server does not require it. Some servers may require it, some servers may request it but not require it, and some servers may not request it at all. It may be the same file as the public key (combined key and certificate file) but this is not recommended. If a password is required to unlock the key, it will be prompted for at the time just prior to establishing the session to the server. 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 of local trusted certificates (see the sslcertpath option). If the server certificate is not signed by one of the trusted ones (directly or indirectly), the SSL connection will fail. This checking should prevent man-in-the-middle attacks against the SSL connection. Note that CRLs are seemingly not currently supported by OpenSSL in certificate verification! Your system clock should be reasonably accurate when using this option!
--sslcertpath <directory>
(Keyword: sslcertpath) Sets the directory fetchmail uses to look up local certificates. The default is your OpenSSL default one. The directory must be hashed as OpenSSL expects it - every time you add or modify a certificate in the directory, you need to 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) in hexadecimal notation with colons separating groups of two digits. The letter hex 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 connection is established. When this is specified, fetchmail will compare the server key fingerprint with the given one, and the connection will fail if they do not match. This can be used to prevent man-in-the-middle attacks.
 

Delivery Control Options

-S <hosts> | --smtphost <hosts>
(Keyword: smtp[host]) Specify a hunt list of hosts to forward mail to (one or more hostnames, comma-separated). Hosts are tried in list order; the first one that is up becomes the forwarding target for the current run. Normally, `localhost' is added to the end of the list as an invisible default. However, when using Kerberos authentication, the FQDN of the machine running fetchmail is added to the end of the list as an invisible default. Each hostname may have a port number following the host name. The port number is separated from the host name by a slash; the default port is 25 (or ``smtp'' under IPv6). If you specify an absolute pathname (beginning with a /), it will be interpreted 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 relay between the ODMR server and SMTP or LMTP receiver.

--fetchdomains <hosts>
(Keyword: fetchdomains) In ETRN or ODMR mode, this option specifies the list of domains the server should ship mail for once the connection is turned around. The default is the FQDN of the machine running fetchmail.
-D <domain> | --smtpaddress <domain>
(Keyword: smtpaddress) Specify the domain to be appended to addresses in RCPT TO lines shipped to SMTP. The name of the SMTP server (as specified by --smtphost, or defaulted to "localhost") is used when this 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 interpreted as a spam-block response from the listener. A value of -1 disables this option. For the command-line option, the list values should be 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. To avoid losing mail, use this option only with MDAs like procmail or sendmail that return a nonzero status on disk-full and other resource-exhaustion errors; the nonzero status tells fetchmail that delivery failed and prevents the message from being deleted off the server. If fetchmail is running as root, it sets its userid to that of the target user while delivering mail through an MDA. Some possible MDAs are "/usr/sbin/sendmail -i -oem -f %F %T", "/usr/bin/deliver" and "/usr/bin/procmail -d %T" (but the latter is usually redundant as it's what SMTP listeners normally forward to). Local delivery addresses will be inserted into the MDA command wherever you place a %T; the mail message's From address will be inserted where you place an %F. Do not use an MDA invocation like "sendmail -i -oem -t" that dispatches on the contents of To/Cc/Bcc, it will create mail loops and bring the just wrath of many postmasters down upon your head.
--lmtp
(Keyword: lmtp) Cause delivery via LMTP (Local Mail Transfer Protocol). A service port must be explicitly specified (with a slash suffix) on each host in the smtphost hunt list if this option is selected; the default 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 SMTP commands that would normally be generated by fetchmail when passing mail to an SMTP listener daemon. An argument of `-' causes the mail to be written to standard output. Note that fetchmail's reconstruction of MAIL FROM and RCPT TO lines is not guaranteed correct; the caveats discussed under THE USE AND ABUSE OF MULTIDROP MAILBOXES below apply.
 

Resource Limit Control Options

-l <maxbytes> | --limit <maxbytes>
(Keyword: limit) Takes a maximum octet size argument. Messages larger than this size will not be fetched and will be left on the server (in foreground sessions, the progress messages will note that they are "oversized"). If the fetch protocol permits (in particular, under IMAP or POP3 without the fetchall option) the message will not be marked seen An explicit --limit of 0 overrides any limits set in your run control file. This option is intended for those needing to strictly control fetch time due to expensive and variable phone rates. In daemon mode, oversize notifications are mailed to the calling user (see the --warnings option). This option does not work with ETRN or ODMR.
-w <interval> | --warnings <interval>
(Keyword: warnings) Takes an interval in seconds. When you call fetchmail with a `limit' option in daemon mode, this controls the interval at which warnings about oversized messages are mailed to the calling user (or the user specified by the `postmaster' option). One such notification is always mailed at the end of the the first poll that the oversized message is detected. Thereafter, renotification is suppressed until after the warning interval elapses (it will take place 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 SMTP listener before the connection is deliberately torn down and rebuilt (defaults to 0, meaning no limit). An explicit --batchlimit of 0 overrides any limits set in your run control file. While sendmail(8) normally initiates delivery of a message immediately after receiving the message terminator, some SMTP listeners are not so prompt. MTAs like (8) may wait till the delivery socket is shut down to deliver. This may produce annoying delays when fetchmail is processing very large batches. Setting the batch limit to some nonzero size will prevent these delays. This option 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 single poll. By default there is no limit. An explicit --fetchlimit of 0 overrides any limits set in your run control file. This option does not work with ETRN or ODMR.
-e <count> | --expunge <count>
(keyword: expunge) Arrange for deletions to be made final after a given number of messages. Under POP2 or POP3, fetchmail cannot make deletions final without sending QUIT and ending the session -- with this option on, fetchmail will break a long mail retrieval session into multiple subsessions, sending QUIT after each sub-session. This is a good defense against line drops on POP3 servers that do not do the equivalent of a QUIT on hangup. Under IMAP, fetchmail normally issues an EXPUNGE command after each deletion in order to force the deletion to be done immediately. This is safest when your connection to the server is flaky and expensive, as it avoids resending duplicate mail after a line hit. However, on large mailboxes the overhead of re-indexing after every message can slam the server pretty hard, so if your connection is reliable it is good to do expunges less frequently. Also note that some servers enforce a delay of a few seconds after each quit, so fetchmail may not be able to get back in immediately after an expunge -- you may see "lock busy" errors if this happens. If you specify this option to an integer N, it tells fetchmail to only issue expunges on every Nth delete. An argument of zero suppresses expunges entirely (so no expunges at all will be done until the end of run). This option does not work with ETRN or ODMR.
 

Authentication Options

-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 running fetchmail. 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 local or remote IP address (or range) before polling. Frequently fetchmail is used over a transient point-to-point TCP/IP link established directly to 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 link is connected to an alternate ISP), your username and password may be vulnerable to snooping (especially when daemon mode automatically polls for mail, shipping a clear password over the net at predictable intervals). The --interface option may be used to prevent this. When the specified link is not up or is not connected to a matching IP address, 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, ppp0 etc.). The field before the second slash is the acceptable IP address. The field after the second slash is a mask which specifies a range of IP addresses to accept. If no mask is present 255.255.255.255 is assumed (i.e. an exact match). This option is currently only supported under Linux and FreeBSD. Please see the monitor section for below for FreeBSD specific information.

-M <interface> | --monitor <interface>
(Keyword: monitor) Daemon mode can cause transient links which are automatically taken down after a period of inactivity (e.g. PPP links) to remain up indefinitely. This option identifies a system TCP/IP interface to be monitored for activity. After each poll interval, if the link is up but no other activity has occurred on the link, then the poll will be skipped. However, when fetchmail is woken up by a signal, the monitor check is skipped and the poll goes through unconditionally. This option is currently only supported under Linux and FreeBSD. For the monitor and interface options to work for non root users under FreeBSD, the fetchmail binary must be installed SGID kmem. This would be a security hole, but fetchmail runs with the effective GID set to that of the kmem group only when interface data is being collected.
--auth <type>
(Keyword: auth[enticate]) This option permits you to specify an authentication type (see USER AUTHENTICATION below for details). The possible values are any, `password', `kerberos_v5' and `kerberos' (or, for excruciating exactness, `kerberos_v4'), gssapi, cram-md5, otp, ntlm, and ssh. When any (the default) is specified, fetchmail tries first methods that don't require a password (GSSAPI, KERBEROS_IV); then it looks for methods that mask your password (CRAM-MD5, X-OTP, NTLM); and only if the server doesn'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 than password, cram-md5, ntlm or otp suppresses fetchmail's normal inquiry for a password. Specify ssh when you are using an end-to-end secure connection such as an ssh tunnel; specify gssapi or kerberos_v4 if you are using a protocol variant that employs GSSAPI or K4. Choosing KPOP protocol automatically selects Kerberos authentication. This option does not work with ETRN.
 

Miscellaneous Options

-f <pathname> | --fetchmailrc <pathname>
Specify a non-default name for the ~/.fetchmailrc run control file. The pathname argument must be either "-" (a single dash, meaning to read the configuration from standard input) or a filename. Unless the --version option is also on, a named file argument must have permissions no more open than 0600 (u=rw,g=,o=) or else be /dev/null.
-i <pathname> | --idfile <pathname>
(Keyword: idfile) Specify an alternate name for the .fetchids file used to save POP3 UIDs.
-n | --norewrite
(Keyword: no rewrite) Normally, fetchmail edits RFC-822 address headers (To, From, Cc, Bcc, and Reply-To) in fetched mail so that any mail IDs local to the server are expanded to full addresses (@ and the mailserver hostname are appended). This enables replies on the client to get addressed correctly (otherwise your mailer might think they should be addressed to local users on the client machine!). This option disables the rewrite. (This option is provided to pacify people who are paranoid about having an MTA edit mail headers and want to know they can prevent it, but it is generally not 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 header fetchmail assumes will carry a copy of the mail's envelope address. Normally this is `X-Envelope-To' but as this header is not standard, practice varies. See the discussion of multidrop address handling below. As a special case, `envelope "Received"' enables parsing of sendmail-style Received lines. This is the default, and it should not be necessary unless 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 user name 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 mail redirection 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 mailbox it puts the username and hostname of the envelope recipient on this line. The major reason for this is to prevent mail loops. To set up qmail to batch mail for a disconnected site the ISP-mailhost will have normally put that site in its `Virtualhosts' control file so it will add a prefix to all mail addresses for this site. This results in mail sent 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 choose but a string matching the user host name is likely. By using the option `envelope Delivered-To:' you can make fetchmail reliably identify 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 a configuration report to standard output. The configuration report is a data structure assignment in the language Python. This option is meant to be used with an interactive ~/.fetchmailrc editor like fetchmailconf, written in Python.

 

USER AUTHENTICATION AND ENCRYPTION

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

If the mailserver is a Unix machine on which you have an ordinary user account, your regular login name and password are used with fetchmail. 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 the client machine as the user-id on the server machine. If you use a different login name on the server machine, specify that login name with the -u option. e.g. if your login name is 'jsmith' on a machine named 'mailgrunt', you would start fetchmail as follows:

fetchmail -u jsmith mailgrunt

The default behavior of fetchmail is to prompt you for your mailserver password before the connection is established. This is the safest way to use fetchmail and ensures that your password will not be compromised. You may also specify your password in your ~/.fetchmailrc file. This is convenient when using fetchmail in daemon mode or with scripts.

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

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

Early versions of POP3 (RFC1081, RFC1225) supported a crude form of independent authentication using the rhosts file on the mailserver side. Under this RPOP variant, a fixed per-user ID equivalent to a password was sent in clear over a link to a reserved port, with the command RPOP rather than PASS to alert the server that it should do special checking. RPOP is supported by fetchmail (you can specify `protocol RPOP' to have the program send `RPOP' rather than `PASS') but its use is strongly discouraged. This facility 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 program to do this with on the server is probably called popauth(8)). You put the same password in your ~/.fetchmailrc file. Each time fetchmail logs in, it sends a cryptographically secure hash of your password and the server greeting time to the server, which can verify it by checking its authorization database.

If your fetchmail was built with Kerberos support and you specify Kerberos authentication (either with --auth or the .fetchmailrc option authenticate kerberos_v4) it will try to get a Kerberos ticket from the mailserver at the start of each query. Note: if either the pollnane or via name is `hesiod', fetchmail will try to use Hesiod to look up the mailserver.

If you use POP3 or IMAP with GSSAPI authentication, fetchmail will expect the server to have RFC1731- or RFC1734-conformant GSSAPI capability, and will use it. Currently this has only been tested over Kerberos V, so you're expected to already have a ticket-granting ticket. You may pass a username different from your principal name using the standard --user command or by the .fetchmailrc option 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 that site entry to stop .fetchmail from asking you for a password when it starts up.

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

Compuserve's RPA authentication (similar to APOP) is supported. If you compile in the support, fetchmail will try to perform an RPA pass-phrase authentication instead of sending over the password en clair if it detects "@compuserve.com" in the hostname.

If you are using IMAP, Microsoft's NTLM authentication (used by Microsoft Exchange) is supported. If you compile in the support, fetchmail will try to perform an NTLM authentication (instead of sending over the password en clair) whenever the server returns AUTH=NTLM in its capability response. Specify a user option value that looks like `user@domain': the part to the left of the @ will be passed as the username and the part to the right as the NTLM domain.

If you are using IPsec, the -T (--netsec) option can be used to pass an IP security request to be used when outgoing IP connections are initialized. You can also do this using the `netsec' server option in the .fetchmailrc file. In either case, the option value is a string 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 .fetchmailrc file. With SSL encryption enabled, queries are initiated over a connection after 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 and no explicit port is specified.

When connecting to an SSL encrypted server, the server presents a certificate to the client for validation. The certificate is checked to verify that the common name in the certificate matches the name of the server being contacted and that the effective and expiration dates in the certificate indicate that it is currently valid. If any of these checks fail, a warning message is printed, but the connection continues. The server certificate does not need to be signed by any specific Certifying Authority and may be a "self-signed" certificate.

Some SSL encrypted servers may request a client side certificate. A client side public SSL certificate and private SSL key may be specified. If requested by the server, the client certificate is sent to the server for validation. Some servers may require a valid client certificate and may refuse connections if a certificate is not provided or if the certificate is not valid. Some servers may require client side certificates be signed by a recognized Certifying Authority. The format for the key files and the 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 mentioned setup with self-signed server certificates retrieved over the wires can protect you from a passive eavesdropper it doesn't help against an active attacker. It's clearly an improvement over sending the passwords in clear but you should be aware that a man-in-the-middle attack is trivially possible (in particular with tools such as dsniff, http://www.monkey.org/~dugsong/dsniff/). Use of an ssh tunnel (see below for some examples) is preferable if you care seriously about the security of your mailbox.

fetchmail also supports authentication to the ESMTP server on the client side according to RFC 2554. You can specify a name/password pair to be used with the keywords `esmtpname' and `esmtppassword'; the former defaults to the username of the calling user.

 

DAEMON MODE

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

In daemon mode, fetchmail puts itself in background and runs forever, querying each specified host 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) once every fifteen minutes.

It is possible to set a polling interval in your ~/.fetchmailrc file by saying `set daemon <interval>', where <interval> is an integer number of seconds. If you do this, fetchmail will always start in daemon mode unless you override it with the command-line option --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 a wakeup signal to the daemon, forcing it to poll mailservers immediately. (The wakeup signal is SIGHUP if fetchmail is running as root, SIGUSR1 otherwise.) The wakeup action also clears any `wedged' flags indicating that connections have wedged due to failed authentication or multiple timeouts.

The option --quit will kill a running daemon process instead of waking it up (if there is 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; its effect is to kill any running daemon before doing what the other options specify in combination with the rc file.

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

The --syslog option (keyword: set syslog) allows you to redirect status and error messages emitted to the syslog(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 which indicate the status of the daemon and the results while fetching mail from the server(s). Error messages for command line options and parsing the .fetchmailrc file are still written to stderr, or to the specified log file. The --nosyslog option turns off use of syslog(3), assuming it's turned on in the ~/.fetchmailrc file, or that the -L or --logfile <file> option was used.

The -N or --nodetach option suppresses backgrounding and detachment of the daemon process from its control terminal. This is primarily useful for debugging. Note that this also causes the logfile option to be ignored (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 polling cycle. This is a robustness feature. It means that if a message is fetched (and thus marked seen by the mailserver) but not delivered locally due to some transient error, it will be re-fetched during the next poll cycle. (The IMAP logic doesn't delete messages until they'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 detected at the beginning of the next poll cycle. When a changed ~/.fetchmailrc is detected, fetchmail rereads it and restarts from scratch (using exec(2); no state information is retained in the new instance). Note also that if you break the ~/.fetchmailrc file's syntax, the new instance will softly and silently vanish away on startup.

 

ADMINISTRATIVE OPTIONS

The --postmaster <name> option (keyword: set postmaster) specifies the last-resort username to which multidrop mail is to be forwarded if no matching local recipient can be found. Normally this is just the user who invoked fetchmail. If the invoking user is root, then the default of this option is the user `postmaster'. Setting postmaster to the empty string causes such mail to be discarded.

The --nobounce option suppresses the normal action of bouncing errors back to the sender in an RFC1894-conformant error message. If nobounce is on, the message 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 a Received header into each message describing its place in the chain of transmission, and tells the MTA it forwards to that the mail came from the machine fetchmail itself is running on. If the invisible option is on, the Received header is suppressed and fetchmail tries to spoof the MTA it forwards to into thinking it came directly from the mailserver host.

The --showdots option (keyword: set showdots) forces fetchmail to show progress dots even 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 Received header on the form "polling {label} account {user}", where {label} is the account label (from the specified rcfile, normally ~/.fetchmailrc) and {user} is the username which is used to log on to the mail server. This header can be used to make filtering email where no useful header information is available and you want mail from different accounts sorted into different mailboxes (this could, for example, occur if you have an account on the same server running a mailing list, and are subscribed to the list using that account). The default is not adding any such header. In .fetchmailrc, this is called `tracepolls'.

 

RETRIEVAL FAILURE MODES

The protocols fetchmail uses to talk to mailservers are next to bulletproof. In normal operation forwarding to port 25, no message is ever deleted (or even marked for deletion) on the host until the SMTP listener on the client side has acknowledged to fetchmail that the message has been either accepted for delivery or rejected due to a spam block.

When forwarding to an MDA, however, there is more possibility of error. Some MDAs are `safe' and reliably return a nonzero status on any delivery error, even one due to temporary resource limits. The well-known procmail(1) program is like this; so are most programs designed as mail transport agents, such as sendmail(1), and exim(1). These programs give back a reliable positive acknowledgement and can be used with the mda option with no risk of mail loss. Unsafe MDAs, though, may return 0 even on delivery failure. If this happens, you will lose mail.

The normal mode of fetchmail is to try to download only `new' messages, leaving untouched (and undeleted) messages you have already read directly on the server (or fetched with a previous fetchmail --keep). But you may find that messages you've already read on the server 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 no representation of `new' or `old' state in messages, so fetchmail must treat all messages as new all the time. But POP2 is obsolete, so this is unlikely.

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

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

Yet another POP3 problem is that if they can't make tempfiles in the user's home directory, some POP3 servers will hand back an undocumented response that causes fetchmail to spuriously report "No mail".

The IMAP code uses the presence or absence of the server flag \Seen to decide whether or not a message is new. Under Unix, it counts on your IMAP server to notice the BSD-style Status flags set by mail user agents and set the \Seen flag from them when appropriate. All Unix IMAP servers we know of do this, though it's not specified by the IMAP RFCs. If you ever trip over a server that doesn't, the symptom will be that messages you have already read on your host will look new to the server. In this (unlikely) case, only messages you fetched with fetchmail --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 flush to the client via SMTP. Therefore it sends only undelivered messages.

 

SPAM FILTERING

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

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

According to RFC2821, the correct thing to return in this situation is 550 "Requested action not taken: mailbox unavailable" (the draft adds "[E.g., mailbox not found, no access, or command rejected for policy reasons].").

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

The postfix MTA runs 554 as an antispam response.

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

Return codes which fetchmail treats as antispam responses and discards the message can be set with the `antispam' option. This is one of the only three circumstance under which fetchmail ever discards mail (the others are the 552 and 553 errors described below, and the suppression of multidropped messages with a message-ID already seen).

If fetchmail is fetching from an IMAP server, the antispam response will be detected and the message rejected immediately after the headers have been fetched, without reading the message body. Thus, you won't pay for downloading spam message bodies.

By default, the list of antispam responses is empty.

If the spambounce option is on, mail that is spam-blocked triggers an RFC1892 bounce message informing the originator that we do not accept mail from it.

 

SMTP/ESMTP ERROR HANDLING

Besides the spam-blocking described above, fetchmail takes special actions 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 the originator.
553 (invalid sending domain)
Delete the message from the server. Don't even try to send bounce-mail to the originator.

Other errors trigger bounce mail back to the originator.

 

THE RUN CONTROL FILE

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

To protect the security of your passwords, when --version is not on your ~/.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 to be executed when fetchmail is called with no arguments.  

Run Control Syntax

Comments begin with a '#' and extend through the end of the line. Otherwise the file consists of a series of server entries or global option 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 contain whitespace (and quoted digits are treated as a string). An unquoted string is any whitespace-delimited token that is neither numeric, string quoted nor contains the special characters `,', `;', `:', or `='.

Any amount of whitespace separates tokens in server entries, but is otherwise ignored. You may use standard C-style escapes (\n, \t, \b, octal, and hex) to embed non-printable characters or string delimiters 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 any number of user descriptions. Note: the most common cause of syntax errors 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 make it resemble English. They're ignored, but but can make entries much easier to read at a glance. The punctuation characters ':', ';' and ',' are also ignored.

 

Poll vs. Skip

The `poll' verb tells fetchmail to query this host when it is run with no arguments. The `skip' verb tells fetchmail not to poll this host unless it is explicitly named on the command line. (The `skip' verb allows you to experiment with test entries safely, or easily disable entries for hosts that are temporarily down.)

 

Keyword/Option Summary

Here are the legal options. Keyword suffixes enclosed in square brackets are optional. Those corresponding to command-line options are followed by `-' and the appropriate option letter.

Here are the legal global options:

T}
set nosyslog     

Here are the legal server options:

T}
plugout     

no dns
Do comparison by IP address for multidrop     
    






    

no checkalias
uidl -U Force POP3 to use client-side UIDLs
Turn off POP3 use of client-side UIDLs (default)



    
    
interval
netsec
principal
esmtpname
esmtppassword

Here are the legal user options:

Remember that all user options must follow all server options.
In the .fetchmailrc file, the `envelope' string argument may be    

    

    

for ignoring bogus Received headers created by an ISP's local delivery


    




agent.
equivalents) can take a space- or comma-separated list of names        






    


    

following them.
All options correspond to the obvious command-line arguments, except
the following: `via', `interval', `aka', `is', `to', `dns'/`no dns',        






    


    

`checkalias'/`no checkalias', `password', `preconnect', `postconnect',
`localdomains', `stripcr'/`no stripcr', `forcecr'/`no forcecr',



    

`dropdelivered/no dropdelivered', `mimedecode/no mimedecode', `idle/no
The `via' option is for if you want to have more        







    

    


    
than one configuration pointing at the same site. If it is present,


    






This will override the argument of poll, which can then simply be a

    


The `interval' option (which takes a numeric argument) allows you to poll a
`interval N' the server this option is attached to will only be





    
    

    
queried every N poll intervals.
The `is' or `to' keywords associate the following local (client)


the mailserver user name in the entry. If an is/to list has `*' as

your username on the client machine is different from your name on the
mailserver. When there is only a single local name, mail is forwarded    
    




and Bcc headers. In this case

    
    



    
fetchmail code does look at the Received, To, Cc, and Bcc
    


    

    
    



    
`aka' or `localdomains' options, and usually also for hostname parts
which DNS tells it are aliases of the mailserver. See the discussion    



    


    








matching addresses are handled.
If fetchmail cannot match any mailserver usernames or





Normally it will be bounced to the sender, but if `nobounce' is on



    
The `dns' option (normally on) controls the way addresses from
multidrop mailboxes are checked. On, it enables logic to check each    
    

host address that doesn't match an `aka' or `localdomains' declaration    




    
    

    
by looking it up with DNS. When a mailserver username is recognized
        

the list of local recipients.    






    
    

    
The `checkalias' option (normally off) extends the lookups performed
by the `dns' keyword in multidrop mode, providing a way to cope with
remote MTAs that identify themselves using their canonical name, while    
    


they're polled using an alias.

    


    
reverts to delivery using the To/Cc/Bcc headers (See below
`Header vs. Envelope addresses').


Specifying this option instructs


    

    
to retrieve all the IP addresses associated with both the poll name
and the name used by the remote MTA and to do a comparison of the IP
addresses. This comes in handy in situations where the remote server    

    





undergoes frequent canonical name changes, that would otherwise







    
    
    
The `aka' option is for use with multidrop mailboxes. It allows you
to pre-declare a list of DNS aliases for a server. This is an
optimization hack that allows you to trade space for speed. When





    

    
    
while processing a multidrop mailbox, grovels through message headers
looking for names of the mailserver, pre-declaring common ones can
save it from having to do DNS lookups. Note: the names you give        
    

as arguments to `aka' are matched as suffixes -- if you specify
(say) `aka netaxs.com', this will match not just a hostnamed


    





    
    

    


(say) pop3.netaxs.com and mail.netaxs.com.
The `localdomains' option allows you to declare a list of domains

    
    

    


address lines in multidrop modes, and a trailing segment of a host
name matches a declared local domain, that address is passed through
to the listener or MDA unaltered (local-name mappings are not    
    

        
    

applied).
If you are using `localdomains', you may also need to specify `no
envelope', which disables fetchmail's normal attempt to deduce    






    

an envelope address from the Received line or X-Envelope-To header or
whatever header has been previously set by `envelope'. If you set `no    
envelope' in the defaults entry it is possible to undo that in    



individual entries by using `envelope <string>'. As a special case,
`envelope "Received"' restores the default parsing of    
Received lines.    


    


    

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


The `preconnect' keyword allows you to specify a shell command to be    

    

executed just before each time
establishes a mailserver connection. This may be useful if you are     
attempting to set up secure POP connections with the aid of    

If the command returns a nonzero status, the poll of that mailserver
will be aborted.    


Similarly, the `postconnect' keyword similarly allows you to specify a    







    

shell command to be executed just after each time a mailserver
connection is taken down.    

The `forcecr' option controls whether lines terminated by LF only are    






    



given CRLF termination before forwarding. Strictly speaking RFC821
requires this, but few MTAs enforce the requirement it so this option    
is normally off (only one such MTA, qmail, is in significant use at            

    


time of writing).
The `stripcr' option controls whether carriage returns are stripped    

out of retrieved mail before it is forwarded. It is normally not    




necessary to set this, because it defaults to `on' (CR stripping
enabled) when there is an MDA declared but `off' (CR stripping    
disabled) when forwarding is via SMTP. If `stripcr' and `forcecr' are    



both on, `stripcr' will override.
The `pass8bits' option exists to cope with Microsoft mail programs that    
stupidly slap a "Content-Transfer-Encoding: 7bit" on everything. With        

    

        
    


this option off (the default) and such a header present,
declares BODY=7BIT to an ESMTP-capable listener; this causes problems for    
messages actually using 8-bit ISO or KOI-8 character sets, which will        







    

be garbled by having the high bits of all characters stripped. If
`pass8bits' is on,

the listener is 8-bit-clean (as all the major ones now are) the right
thing will probably result.
    

X-Mozilla-Status lines are retained in fetched mail (the default) or
discarded. Retaining them allows your MUA to see what messages (if
any) were marked seen on the server. On the other hand, it can

    
    


    
    

confuse some new-mail notifiers, which assume that anything with a
Status line in it has been seen. (Note: the empty Status lines
inserted by some buggy POP servers are unconditionally discarded.)


    
    


    
    

The `dropdelivered' option controls wether Delivered-To headers will
be kept in fetched mail (the default) or discarded. These headers are     
added by Qmail and Postfix mailservers in order to avoid mail loops but    
    
    



    
    

may get in your way if you try to "mirror" a mailserver within the same
domain. Use with caution.


The `mimedecode' option controls whether MIME messages using the



    
    

    




quoted-printable encoding are automatically converted into pure 8-bit
data. If you are delivering mail to an ESMTP-capable, 8-bit-clean
    
    





    
    


this will automatically convert quoted-printable message headers and
data into 8-bit data, making it easier to understand when reading
mail. If your e-mail programs know how to deal with MIME messages,
then this option is not needed. The mimedecode option is off by
default, because doing RFC2047 conversion on headers throws away
character-set information and can lead to bad results if the encoding
of the headers differs from the body encoding.
The `idle' option is usable only with IMAP servers supporting the
RFC2177 IDLE command extension. If it is enabled, and fetchmail
detects that IDLE is supported, an IDLE will be issued at the end
of each poll. This will tell the IMAP server to hold the connection
open and notify the client when new mail is available. If you need to
poll a link frequently, IDLE can save bandwidth by eliminating TCP/IP
connects and LOGIN/LOGOUT sequences. On the other hand, an IDLE
connection will eat almost all of your fetchmail's time, because it
will never drop the connection and allow other pools to occur unless
the server times out the IDLE. It also doesn't work with multiple
folders; only the first folder will ever be polled.
The `properties' option is an extension mechanism. It takes a string
argument, which is ignored by fetchmail itself. The string argument may be
used to store configuration information for scripts which require it.
In particular, the output of `--configdump' option will make properties
associated with a user entry readily available to a Python script.
The words `here' and `there' have useful English-like
significance. Normally `user eric is esr' would mean that
mail 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 a
password (the password may be plaintext or subject to
protocol-specific encryption as in APOP); `kerberos' tells
fetchmail to try to get a Kerberos ticket at the start of each
query instead, and send an arbitrary string as the password; and
`gssapi' tells fetchmail to use GSSAPI authentication. See the description
of the `auth' keyword for more.
Specifying `kpop' sets POP3 protocol over port 1109 with Kerberos V4
authentication. 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. A
command-line --logfile option will override this. Also, `set daemon'
sets the poll interval as --daemon does. This can be overridden by a
command-line --daemon option; in particular --daemon 0 can be used to
force foreground operation. The `set postmaster' statement sets the
address to which multidrop mail defaults if there are no local
matches. 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 FROM
address when forwarding to SMTP. This order is intended to cope
gracefully with receiving mailing list messages in multidrop mode. The
intent is that if a local address doesn't exist, the bounce message
won't be returned blindly to the author or to the list itself, but
rather 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 is
specified by the `envelope' option) to determine the local
recipient 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 and
have precedence over their To:/Cc:/Bcc: counterparts. If the Resent-*
lines doesn't exist, the To:, Cc:, Bcc: and Apparently-To: lines are
looked for. (The presence of a Resent-To: is taken to imply that the
person referred by the To: address has already received the original
copy of the mail).
Note that although there are password declarations in a good many
of the examples below, this is mainly for illustrative purposes.
We recommend stashing account/password pairs in your $HOME/.netrc
file, where they can be used not just by fetchmail but by ftp(1) and
other 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 significantly
more (parsing is done only once, at startup time).
If you need to include whitespace in a parameter string, enclose the
string 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 record
is interpreted as defaults for all queries to use. It may be overwritten
by 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 only
likely to be useful when running fetchmail in daemon mode as root).
The `user' keyword leads off a user description, and every user specification
in 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.net
username `jsmith' and the local username `jjones' with the
pop.provider.net username `jones'. Mail for `jones' is kept on the
server after download.
Here's what a simple retrieval configuration for a multi-drop mailbox
looks 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 a
multi-drop box, and that messages in it should be parsed for the
server user names `golux', `hurkle', and `snark'. It further
specifies that `golux' and `snark' have the same name on the
client as on the server, but mail for server user `hurkle' should be
delivered 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 is
a multi-drop box. It tells fetchmail that any address in the
loonytoons.org or toons.org domains (including subdomain addresses like
`joe@daffy.loonytoons.org') should be passed through to the local SMTP
listener without modification. Be careful of mail loops if you do this!
Here's an example configuration using ssh and the plugin option. The
queries 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;
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. A
piece of mail is considered duplicate if it has the same message-ID as
the message immediately preceding and more than one addressee. Such
runs of messages may be generated when copies of a message addressed
to multiple users are delivered to a multidrop box.
The fundamental problem is that by having your mailserver toss several
peoples' mail in a single maildrop box, you may have thrown away
potentially vital information about who each piece of mail was
actually addressed to (the `envelope address', as opposed to the
header addresses in the RFC822 To/Cc/Bcc headers). This `envelope
address' is the address you need in order to reroute mail properly.
Sometimes
can deduce the envelope address. If the mailserver MTA is
and the item of mail had just one recipient, the MTA will have written
a `by/for' clause that gives the envelope addressee into its Received
header. But this doesn't work reliably for other MTAs, nor if there is
more than one recipient. By default, fetchmail looks for
envelope 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 header
in each message containing a copy of the envelope addresses. This
header (when it exists) is often `X-Envelope-To'. Fetchmail's
assumption about this can be changed with the -E or `envelope' option.
Note that writing an envelope header of this kind exposes the names of
recipients (including blind-copy recipients) to all receivers of the
messages; it is therefore regarded by some administrators as a
security/privacy problem.
A slight variation of the `X-Envelope-To' header is the `Delivered-To' put
by qmail to avoid mail loops. It will probably prefix the user name with a
string that normally matches the user's domain. To remove this prefix you
can use the -Q or `qvirtual' option.
Sometimes, unfortunately, neither of these methods works. When they
all fail, fetchmail must fall back on the contents of To/Cc/Bcc
headers to try to determine recipient addressees -- and these are not
reliable. In particular, mailing-list software often ships mail with
only the list broadcast address in the To header.
When
cannot deduce a recipient address that is local, and the intended
recipient 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 Bcc
information is carried only as envelope address (it's not put
in the headers fetchmail can see unless there is an X-Envelope
header). Thus, blind-copying to someone who gets mail over a
fetchmail link will fail unless the the mailserver host routinely
writes X-Envelope or an equivalent header into messages in your maildrop.
Multiple local names can be used to administer a mailing list from the
client side of a fetchmail collection. Suppose your name is
`esr', and you want to both pick up your own mail and maintain a mailing
list called (say) "fetchmail-friends", and you want to keep the alias
list on your client machine.
On your server, you can alias `fetchmail-friends' to `esr'; then, in
your .fetchmailrc, declare `to esr fetchmail-friends here'.
Then, when mail including `fetchmail-friends' as a local address
gets fetched, the list name will be appended to the list of
recipients your SMTP listener sees. Therefore it will undergo alias
expansion locally. Be sure to include `esr' in the local alias
expansion of fetchmail-friends, or you'll never see mail sent only to
the list. Also be sure that your listener has the "me-too" option set
(sendmail's -oXm command-line option or OXm declaration) so your name
isn't removed from alias expansions in messages you send.
This trick is not without its problems, however. You'll begin to see
this when a message comes in that is addressed only to a mailing list
you do not have declared as a local name. Each such message
will feature an `X-Fetchmail-Warning' header which is generated
because fetchmail cannot find a valid local name in the recipient
addresses. Such messages default (as was described above) to being
sent to the local user running
but the program has no way to know that that's actually the right thing.
Multidrop mailboxes and
serving multiple users in daemon mode do not mix. The problem, again, is
mail from mailing lists, which typically does not have an individual
recipient address on it. Unless
can deduce an envelope address, such mail will only go to the account
running fetchmail (probably root). Also, blind-copied users are very
likely never to see their mail at all.
If you're tempted to use
to retrieve mail for multiple users from a single mail drop via POP or
IMAP, think again (and reread the section on header and envelope
addresses above). It would be smarter to just let the mail sit in the
mailserver's queue and use fetchmail's ETRN or ODMR modes to trigger
SMTP sends periodically (of course, this means you have to poll more
frequently than the mailserver's expiry period). If you can't arrange
this, try setting up a UUCP feed.
If you absolutely must use multidrop for this purpose, make sure
your mailserver writes an envelope-address header that fetchmail can
see. Otherwise you will lose mail and it will come back
to haunt you.
Normally, when multiple users are declared
extracts recipient addresses as described above and checks each host
part with DNS to see if it's an alias of the mailserver. If so, the
name mappings described in the to ... here declaration are done and
the mail locally delivered.
This is the safest but also slowest method. To speed it up,
pre-declare mailserver aliases with `aka'; these are checked before
DNS lookups are done. If you're certain your aka list contains
DNS aliases of the mailserver (and all MX names pointing at it)
you can declare `no dns' to suppress DNS lookups entirely and
only match against the aka list.
To facilitate the use of
in shell scripts, an exit code is returned to give an indication
of what occurred during a given connection.
The exit codes returned by
are as follows:
One or more messages were successfully retrieved (or, if the -c option
was selected, were found waiting but not retrieved).
There was no mail awaiting retrieval. (There may have been old mail still
on the server but not selected for retrieval.)
An error was encountered when attempting to open a socket to retrieve
mail. 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 be
because a protocol fetchmail wants to use is not listed in /etc/services.
The user authentication step failed. This usually means that a bad
user-id, password, or APOP id was specified. Or it may mean that you
tried to run fetchmail under circumstances where it did not have
standard input attached to a terminal and could not prompt for a
missing password.
Some sort of fatal protocol error was detected.
There was a syntax error in the arguments to
The run control file had bad permissions.
There was an error condition reported by the server. Can also
fire if
timed out while waiting for the server.
Client-side exclusion error. This means
either found another copy of itself already running, or failed in such
a way that it isn't sure whether another copy is running.
The user authentication step failed because the server responded "lock
busy". Try again after a brief pause! This error is not implemented
for all protocols, nor for all servers. If not implemented for your
server, "3" will be returned instead, see above. May be returned when
talking to qpopper or other servers that can respond with "lock busy"
or some similar text containing the word "lock".
The
run failed while trying to do an SMTP port open or transaction.
Fatal DNS error. Fetchmail encountered an error while performing
a DNS lookup at startup and could not proceed.
BSMTP batch file could not be opened.
Poll terminated by a fetch limit (see the --fetchlimit option).
Server busy indication.
Internal error. You should see a message on standard error with
details.
When
queries more than one host, return status is 0 if any query
successfully retrieved mail. Otherwise the returned error status is
that 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 the
UIDL 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 for
passwords 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 the
calling user (default local name) for purposes such as mailing error
notifications. Otherwise, if either the LOGNAME or USER variable is
correctly set (e.g. the corresponding UID matches the session user ID)
then that name is used as the default local name. Otherwise
getpwuid(3) must be able to retrieve a password entry for the
session ID (this elaborate logic is designed to handle the case of
multiple names per userid gracefully).
If the environment variable FETCHMAILHOME is set to a valid and
existing directory name, the .fetchmailrc and .fetchids and
.fetchmail.pid files are put there instead of in the invoking user's
home directory (and lose the leading dots on their names). The
.netrc file is looked for in the the invoking user's home directory
regardless of FETCHMAILHOME's setting.
If a
daemon is running as root, SIGHUP wakes it up from its sleep phase and
forces a poll of all non-skipped servers (this is in accordance with
the usual conventions for system daemons).
If
is running in daemon mode as non-root, use SIGUSR1 to wake it (this is
so SIGHUP due to logout can retain the default action of killing it).
Running
in foreground while a background fetchmail is running will do
whichever of these is appropriate to wake it up.
The mda and plugin options interact badly. In order to collect error
status from the MDA, fetchmail has to change its normal signal
handling so that dead plugin processes don't get reaped until the end
of the poll cycle. This can cause resource starvation if too many
zombies accumulate. So either don't deliver to a MDA using plugins or
risk 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 of
quoting and embedded comments are likely to confuse it.
In a message with multiple envelope headers, only the last one
processed will be visible to fetchmail. To get around this, use a
mailserver-side filter that consolidates the contents of all envelope
headers into a single one (procmail, mailagent, or maildrop can be
programmed to do this fairly easily).
Use of some of these protocols requires that the program send
unencrypted passwords over the TCP/IP connection to the mailserver.
This creates a risk that name/password pairs might be snaffled with a
packet sniffer or more sophisticated monitoring software. Under Linux
and FreeBSD, the --interface option can be used to restrict polling to
availability of a specific interface device with a specific local or
remote IP address, but snooping is still possible if (a) either host
has a network device that can be opened in promiscuous mode, or (b)
the intervening network link can be tapped. We recommend the use of
tunnelling to not only shroud your passwords but encrypt the entire
conversation.
Use of the %F or %T escapes in an mda option could open a security
hole, because they pass text manipulable by an attacker to a shell
command. Potential shell characters are replaced by `_' before
execution. The hole is further reduced by the fact that fetchmail
temporarily discards any suid privileges it may have while running the
MDA. 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 that
port 25 of localhost be available for sending mail via SMTP.
If you modify a
while a background instance is running and break the syntax, the
background instance will die silently. Unfortunately, it can't
die noisily because we don't yet know whether syslog should be enabled.
On some systems, fetchmail dies quietly even if there is no syntax
error; this seems to have something to do with buggy terminal ioctl
code in the kernel.
The -f - option (reading a configuration from stdin) is incompatible
with the plugin option.
The UIDL code is generally flaky and tends to lose its state on errors
and line drops (so that old messages are re-seen). If this happens to
you, switch to IMAP4.
The `principal' option only handles Kerberos IV, not V.
Send comments, bug reports, gripes, and the like to the
fetchmail-friends list <fetchmail-friends@lists.ccil.org>. An HTML FAQ is
available at the fetchmail home page; surf to
http://www.tuxedo.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 to
name here have contributed code and patches.
This program is descended from and replaces
by Carl Harris <ceharris@mal.com>; the internals have become quite different,
but some of its interface design is directly traceable to that
ancestral 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.

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