fetchmail reference manual fetchmail(1)
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 han-
dle 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 support-
ing any of the common mail-retrieval protocols: POP2
(legacy, to be removed from future release), POP3, IMAP2bis,
IMAP4, and IMAP4rev1. It can also use the ESMTP ETRN exten-
sion 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 P 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.
If fetchmail is used with a POP or an IMAP server, it has
two fundamental modes of operation for each user account
from which it retrieves mail: singledrop- and multidrop-
mode. In singledrop-mode, fetchmail assumes that all mes-
sages in the user's account are intended for a single reci-
pient. An individual mail message will not be inspected for
recipient information, rather, the identity of the recipient
will either default to the local user currently executing
fetchmail, or else will need to be explicitly specified in
the configuration file. Singledrop-mode is used when the
fetchmailrc configuration contains at most a single local
user specification for a given server account.
With multidrop-mode, fetchmail is not able to assume that
there is only a single recipient, but rather that the mail
server account actually contains mail intended for any
number of different recipients. Therefore, fetchmail must
attempt to deduce the proper "envelope recipient" from the
mail headers of each message. In this mode of operation,
fetchmail almost resembles an MTA, however it is important
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to note that neither the POP nor IMAP protocols were
intended for use in this fashion, and hence envelope infor-
mation is often not directly available. Instead, fetchmail
must resort to a process of informed guess-work in an
attempt to discover the true envelope recipient of a mes-
sage, unless the ISP stores the envelope information in some
header (not all do). Even if this information is present in
the headers, the process can be error-prone and is dependent
upon the specific mail server used for mail retrieval.
Multidrop-mode is used when more than one local user is
specified for a particular server account in the configura-
tion file. Note that the forgoing discussion of singledrop-
and multidrop-modes does not apply to the ESMTP ETRN or ODMR
retrieval methods, since they are based upon the SMTP proto-
col which specifically provides the envelope recipient to
fetchmail.
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. fetchmail provides the SMTP server with
an envelope recipient derived in the manner described previ-
ously. 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, postfix, or qmail). All the delivery-control mechan-
isms (such as .forward files) normally available through
your system MDA and local delivery agents will therefore
work automatically.
If no port 25 listener is available, but your fetchmail con-
figuration was told about a reliable local MDA, it will use
that MDA for local delivery instead.
If the program fetchmailconf is available, it will assist
you in setting up and editing a fetchmailrc configuration.
It runs under the X window system and requires that the
language Python and the Tk toolkit be present on your sys-
tem. 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 prob-
lems 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
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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 docu-
mented 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 mail-
box 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 output during a
fetch (but does not suppress actual error messages).
The --verbose option overrides this.
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-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 (since v6.3.3)
(Keyword: fetchall, since v3.0) 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. While the -a and --all command-line and
fetchall rcfile options have been supported for a long
time, the --fetchall command-line option was added in
v6.3.3.
-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. If used
with POP3, it is recommended to also specify the --uidl
option or uidl keyword.
-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. This is a dangerous option and can
cause mail loss when used improperly. It deletes old
(seen) messages from the mailserver before retrieving
new messages. Warning: This can cause mail loss if you
check your mail with other clients than fetchmail, and
cause fetchmail to delete a message it had never
fetched before. It can also cause mail loss if the
mail server marks the message seen after retrieval
(IMAP2 servers). You should probably not use this
option in your configuration file. If you use it with
POP3, you must use the 'uidl' option. What you probably
want is the default setting: if you don't specify '-k',
then fetchmail will automatically delete messages after
successful delivery.
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--limitflush
POP3/IMAP only, since version 6.3.0. Delete oversized
messages from the mailserver before retrieving new mes-
sages. The size limit should be separately specified
with the --limit option. This option does not work
with ETRN or ODMR.
Protocol and Query Options
-p --proto
(Keyword: proto[col]) Specify the protocol to use when
communicating with the remote mailserver. If no proto-
col 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 (legacy, to be removed from
future release)
POP3 Post Office Protocol 3
APOP Use POP3 with old-fashioned MD5-challenge authen-
tication. Considered not resistant to man-in-
the-middle attacks.
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 automati-
cally detects 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 (com-
municating 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.
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-U --uidl
(Keyword: uidl) Force UIDL use (effective only with
POP3). Force client-side tracking of 'newness' of mes-
sages (UIDL stands for "unique ID listing" and is
described in RFC1939). Use with 'keep' to use a mail-
box 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. Note that fetchmail may automatically enable
this option depending on upstream server capabilities.
Note also that this option may be removed and forced
enabled in a future fetchmail version. See also:
--idfile.
--idle (since 6.3.3)
(Keyword: idle, since before 6.0.0) Enable IDLE use
(effective only with IMAP). Note that this works with
only one folder at a given time. While the idle rcfile
keyword had been supported for a long time, the --idle
command-line option was added in version 6.3.3. IDLE
use means that fetchmail tells the IMAP server to send
notice of new messages, so they can be retrieved sooner
than would be possible with regular polls.
-P --service
(Keyword: service) Since version 6.3.0. The service
option permits you to specify a service name to connect
to. You can specify a decimal port number here, if
your services database lacks the required service-port
assignments. See the FAQ item R12 and the --ssl docu-
mentation for details. This replaces the older --port
option.
--port
(Keyword: port) Obsolete version of --service that does
not take service names. Note: this option may be
removed from a future version.
--principal
(Keyword: principal) The principal option permits you
to specify a service principal for mutual authentica-
tion. This is applicable to POP3 or IMAP with Kerberos
authentication.
-t --timeout
(Keyword: timeout) The timeout option allows you to set
a server-nonresponse timeout in seconds. If a mail-
server 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
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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 hap-
pens.
--plugin
(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 SL, 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
(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 --folder
(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 fetchmail to poll trace
information in the form 'polling %s account %s' and
'folder %s' to the Received line it generates, where
the %s parts are replaced by the user's remote name,
the poll label, and the folder (mailbox) where avail-
able (the Received header also normally includes the
server's true name). This can be used to facilitate
mail filtering based on the account it is being
received from. The folder information is written only
since version 6.3.4.
--ssl
(Keyword: ssl) Causes the connection to the mail server
to be encrypted via SL. Connect to the server using
the specified base protocol over a connection secured
by SL. This option defeats TLS negotiation. Use
--sslcertck to validate the certificates presented by
the server.
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Note that fetchmail may still try to negotiate TLS even
if this option is not given. You can use the --sslproto
option to defeat this behavior or tell fetchmail to
negotiate a particular SL protocol.
If no port is specified, the connection is attempted to
the well known port of the SL version of the base pro-
tocol. 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 SL
secured protocol, for POP3, it is port 110 for the
clear text and port 995 for the encrypted variant.
If your system lacks the corresponding entries from
/etc/services, see the --service option and specify the
numeric port number as given in the previous paragraph
(unless your ISP had directed you to different ports,
which is uncommon however).
--sslcert
(Keyword: sslcert) Specifies the file name of the
client side public SL certificate. Some SL 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 certifi-
cate to be presented to the server at the time the SL
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 (com-
bined key and certificate file) but this is not recom-
mended.
NOTE: If you use client authentication, the user name
is fetched from the certificate's CommonName and over-
rides the name set with --user.
--sslkey
(Keyword: sslkey) Specifies the file name of the client
side private SL key. Some SL encrypted servers may
require client side keys and certificates for authenti-
cation. In most cases, this is optional. This speci-
fies the location of the private key used to sign tran-
sactions with the server at the time the SL 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
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prompted for at the time just prior to establishing the
session to the server. This can cause some complica-
tions in daemon mode.
--sslproto
(Keyword: sslproto) Forces an SL or TLS protocol. Pos-
sible values are 'SL2', 'SL3', 'SL23', and 'TLS1'.
Try this if the default handshake does not work for
your server. Use this option with negotiation when the
server advertises STARTLS or STLS, use ''. This
option, even if the argument is the empty string, will
also suppress the diagnostic 'SERVER: opportunistic
upgrade to TLS.' message in verbose mode. The default
is to try appropriate protocols depending on context.
--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 cannot be obtained or is not signed
by one of the trusted ones (directly or indirectly),
the SL connection will fail, regardless of the
sslfingerprint option. Note that CRL are only sup-
ported in OpenSL 0.9.7 and newer! Your system clock
should also be reasonably accurate when using this
option.
Note that this optional behavior may become default
behavior in future fetchmail versions.
--sslcertpath
(Keyword: sslcertpath) Sets the directory fetchmail
uses to look up local certificates. The default is your
OpenSL default one. The directory must be hashed as
OpenSL expects it - every time you add or modify a
certificate in the directory, you need to use the
crehash tool (which comes with OpenSL 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 OpenSL uses, and the one fetchmail
uses to report the fingerprint when an SL 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
regardless of the sslcertck setting. The connection
will also fail if fetchmail cannot obtain an SL certi-
ficate from the server. This can be used to prevent
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man-in-the-middle attacks, but the finger print from
the server needs to be obtained or verified over a
secure channel, and certainly not over the same Inter-
net connection that fetchmail would use.
Using this option will prevent printing certificate
verification errors as long as --sslcertck is unset.
To obtain the fingerprint of a certificate stored in
the file cert.pem, try:
openssl x509 -in cert.pem -noout -md5 -fingerprint
For details, see x509(1ssl).
Delivery Control Options
-S --smtphost
(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. If this option is not specified,
'localhost' is used as the 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 "smtp". If you specify an absolute
path name (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) Exam-
ple:
--smtphost server1,server2/2525,server3,/var/imap/socket/lmtp
This option can be used with ODMR, and will make fetch-
mail a relay between the ODMR server and SMTP or LMTP
receiver.
--fetchdomains
(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 fetch-
mail.
-D --smtpaddress
(Keyword: smtpaddress) Specify the domain to be
appended to addresses in RCPT TO lines shipped to SMTP.
When this is not specified, the name of the SMTP server
(as specified by --smtphost) is used for SMTP/LMTP and
'localhost' is used for UNIX socket/BSMTP.
--smtpname
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(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 --antispam
(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 --mda
(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 maildrop or MTAs like 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 user id to
that of the target user while delivering mail through
an MDA. Some possible MDAs are "/usr/sbin/sendmail -i
-f %F -- %T" (Note: some several older or vendor send-
mail versions mistake -- for an address, rather than an
indicator to mark the end of the option arguments),
"/usr/bin/deliver" and "/usr/bin/maildrop -d %T".
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 ENCLOSE THE %F OR %T STRING IN SINGLE QUOTES!
For both %T and %F, fetchmail encloses the addresses in
single quotes ('), after removing any single quotes
they may contain, before the MDA command is passed to
the shell.
Do NOT use an MDA invocation that dispatches on the
contents of To/Cc/Bcc, like "sendmail -i -t" or
"qmail-inject", it will create mail loops and bring the
just wrath of many postmasters down upon your head.
This is one of the most frequent configuration errors!
Also, do not try to combine multidrop mode with an MDA
such as maildrop that can only accept one address,
unless your upstream stores one copy of the message per
recipient and transports the envelope recipient in a
header; you will lose mail.
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The well-known procmail(1) package is very hard to con-
figure properly, it has a very nasty "fall through to
the next rule" behavior on delivery errors (even tem-
porary ones, such as out of disk space if another
user's mail daemon copies the mailbox around to purge
old messages), so your mail will end up in the wrong
mailbox sooner or later. The proper procmail configura-
tion is outside the scope of this document. Using mail-
drop(1) is usually much easier, and many users find the
filter syntax used by maildrop easier to understand.
Finally, we strongly advise that you do not use qmail-
inject. The command line interface is non-standard
without providing benefits for typical use, and fetch-
mail makes no attempts to accomodate qmail-inject's
deviations from the standard. Some of qmail-inject's
command-line and environment options are actually
dangerous and can cause broken threads, non-detected
duplicate messages and forwarding loops.
--lmtp
(Keyword: lmtp) Cause delivery via LMTP (Local Mail
Transfer Protocol). A service host and port must be
explicitly specified on each host in the smtphost hunt
list (see above) if this option is selected; the
default port 25 will (in accordance with RFC 2033) not
be accepted.
--bsmtp
(keyword: bsmtp) Append fetched mail to a BSMTP file.
This simply contains the SMTP commands that would nor-
mally 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 --limit
(Keyword: limit) Takes a maximum octet size argument,
where 0 is the default and also the special value
designating "no limit". If nonzero, messages larger
than this size will not be fetched and will be left on
the server (in foreground sessions, the progress mes-
sages 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.
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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.
Combined with --limitflush, it can be used to delete
oversized messages waiting on a server. 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 --warnings
(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, re-notification is suppressed
until after the warning interval elapses (it will take
place at the end of the first following poll).
-b --batchlimit
(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 smail(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 --fetchlimit
(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.
--fetchsizelimit
(Keyword: fetchsizelimit) Limit the number of sizes of
messages accepted from a given server in a single tran-
saction. This option is useful in reducing the delay
in downloading the first mail when there are too many
mails in the mailbox. By default, the limit is 100.
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If set to 0, sizes of all messages are downloaded at
the start. This option does not work with ETRN or
ODMR. For POP3, the only valid non-zero value is 1.
--fastuidl
(Keyword: fastuidl) Do a binary instead of linear
search for the first unseen UID. Binary search avoids
downloading the UIDs of all mails. This saves time
(especially in daemon mode) where downloading the same
set of UIDs in each poll is a waste of bandwidth. The
number 'n' indicates how rarely a linear search should
be done. In daemon mode, linear search is used once
followed by binary searches in 'n-1' polls if 'n' is
greater than 1; binary search is always used if 'n' is
1; linear search is always used if 'n' is 0. In non-
daemon mode, binary search is used if 'n' is 1; other-
wise linear search is used. The default value of 'n' is
4. This option works with POP3 only.
-e --expunge
(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 sub-sessions, sending QUIT after each
sub-session. This is a good defense against line drops
on POP3 servers. 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 --user
(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
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fetchmail reference manual fetchmail(1)
client machine that is running fetchmail. See USER
AUTHENTICATION below for a complete description.
-I --interface
(Keyword: interface) Require that a specific interface
device be up and have a specific local or remote IPv4
(IPv6 is not supported by this option yet) 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 P. 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 pass-
word 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.
Note that this option may be removed from a future
fetchmail version.
-M --monitor
(Keyword: monitor) Daemon mode can cause transient
links which are automatically taken down after a period
of inactivity (e.g. P links) to remain up indefin-
itely. This option identifies a system TCP/IP inter-
face 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 sup-
ported 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
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fetchmail reference manual fetchmail(1)
only when interface data is being collected.
Note that this option may be removed from a future
fetchmail version.
--auth
(Keyword: auth[enticate]) This option permits you to
specify an authentication type (see USER AUTHENTICATION
below for details). The possible values are any, pass-
word, kerberosv5, kerberos (or, for excruciating
exactness, kerberosv4), gssapi, cram-md5, otp, ntlm,
msn (only for POP3), external (only IMAP) and ssh.
When any (the default) is specified, fetchmail tries
first methods that don't require a password (EXTERNAL,
GSAPI, KERBEROS IV, KERBEROS 5); then it looks for
methods that mask your password (CRAM-MD5, X-OTP - note
that NTLM and MSN are not autoprobed for POP3 and MSN
is only supported for POP3); 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
and is thus useful for IMAP PREAUTH). (external
suppresses authentication and is thus useful for IMAP
EXTERNAL). Any value other than password, cram-md5,
ntlm, msn 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 external when you use TLS with client authenti-
cation and specify gssapi or kerberosv4 if you are
using a protocol variant that employs GSAPI or K4.
Choosing KPOP protocol automatically selects Kerberos
authentication. This option does not work with ETRN.
Miscellaneous Options
-f --fetchmailrc
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 per-
missions no more open than 0600 (u=rw,g=,o=) or else be
/dev/null.
-i --idfile
(Keyword: idfile) Specify an alternate name for the
.fetchids file used to save POP3 UIDs. NOTE: since
fetchmail 6.3.0, write access to the directory contain-
ing the idfile is required, as fetchmail writes a tem-
porary file and renames it into the place of the real
idfile only if the temporary file has been written suc-
cessfully. This avoids the truncation of idfiles when
running out of disk space.
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fetchmail reference manual fetchmail(1)
--pidfile
(Keyword: pidfile; since fetchmail v6.3.4) Override the
default location of the PID file. Default: see
"ENVIRONMENT" below.
-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 gen-
erally not a good idea to actually turn off rewrite.)
When using ETRN or ODMR, the rewrite option is ineffec-
tive.
-E --envelope
(Keyword: envelope; Multidrop only)
In the configuration file, an enhanced syntax is used:
envelope []
This option changes the header fetchmail assumes will
carry a copy of the mail's envelope address. Normally
this is 'X-Envelope-To'. Other typically found headers
to carry envelope information are 'X-Original-To' and
'Delivered-To'. Now, since these headers are not
standardized, 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, but discouraged
because it is not fully reliable.
Note that fetchmail expects the Received-line to be in
a specific format: It must contain "by host for
address", where host must match one of the mailserver
names that fetchmail recognizes for the account in
question.
The optional count argument (only available in the con-
figuration file) determines how many header lines of
this kind are skipped. A count of 1 means: skip the
first, take the second. A count of 2 means: skip the
first and second, take the third, and so on.
-Q --qvirtual
(Keyword: qvirtual; Multidrop only) The string prefix
assigned to this option will be removed from the user
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fetchmail reference manual fetchmail(1)
name found in the header specified with the envelope
option (before doing multidrop name mapping or local-
domain 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.example.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.
Removed Options
-T --netsec
Removed before version 6.3.0, the required underlying
inet6apps library had been discontinued and is no
longer available.
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
fetchmail Last change: fetchmail 6.3.8 18
fetchmail reference manual fetchmail(1)
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 con-
venient when using fetchmail in daemon mode or with scripts.
Using netrc files
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. To show a prac-
tical example, a .netrc might look like this:
machine hermes.example.org
login joe
password topsecret
You can repeat this block with different user information if
you need to provide more than one password.
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.
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fetchmail reference manual fetchmail(1)
POP3 VARIANTS
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
PAS 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 'PAS')
but its use is strongly discouraged, and support will be
removed from a future fetchmail version. 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 (on
some servers, the program to do this is called popauth(8)).
You put the same password in your ~/.fetchmailrc file. Each
time fetchmail logs in, it sends an MD5 hash of your pass-
word and the server greeting time to the server, which can
verify it by checking its authorization database.
Note that APOP is no longer considered resistant against
man-in-the-middle attacks.
RETR or TOP
fetchmail makes some efforts to make the server believe mes-
sages had not been retrieved, by using the TOP command with
a large number of lines when possible. TOP is a command
that retrieves the full header and a fetchmail-specified
amount of body lines. It is optional and therefore not
implemented by all servers, and some are known to implement
it improperly. On many servers however, the RETR command
which retrieves the full message with header and body, sets
the "seen" flag (for instance, in a web interface), whereas
the TOP command does not do that.
fetchmail will always use the RETR command if "fetchall" is
set. fetchmail will also use the RETR command if "keep" is
set and "uidl" is unset. Finally, fetchmail will use the
RETR command on Maillennium POP3/PROXY servers (used by Com-
cast) to avoid a deliberate TOP misinterpretation in this
server that causes message corruption.
In all other cases, fetchmail will use the TOP command. This
implies that in "keep" setups, "uidl" must be set if "TOP"
is desired.
Note that this description is true for the current version
of fetchmail, but the behavior may change in future ver-
sions. In particular, fetchmail may prefer the RETR command
because the TOP command causes much grief on some servers
and is only optional.
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fetchmail reference manual fetchmail(1)
ALTERNATE AUTHENTICATION FORMS
If your fetchmail was built with Kerberos support and you
specify Kerberos authentication (either with --auth or the
.fetchmailrc option authenticate kerberosv4) it will try to
get a Kerberos ticket from the mailserver at the start of
each query. Note: if either the pollname or via name is
'hesiod', fetchmail will try to use Hesiod to look up the
mailserver.
If you use POP3 or IMAP with GSAPI authentication, fetch-
mail will expect the server to have RFC1731- or RFC1734-
conforming GSAPI 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 nor-
mal 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 use client authentication with TLS1 and your IMAP
daemon returns the AUTH=EXTERNAL response, fetchmail will
notice this and will use the authentication shortcut and
will not send the passphrase. In this case you can declare
the authentication value 'external'
on that site to stop fetchmail from asking you for a pass-
word 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 unen-
crypted.
Compuserve's RPA authentication 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 authentica-
tion (instead of sending over the password en clair) when-
ever 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
fetchmail Last change: fetchmail 6.3.8 21
fetchmail reference manual fetchmail(1)
domain.
Secure Socket Layers (SL) and Transport
You can access SL encrypted services by specifying the
--ssl option. You can also do this using the "ssl" user
option in the .fetchmailrc file. With SL encryption
enabled, queries are initiated over a connection after nego-
tiating an SL session, and the connection fails if SL can-
not be negotiated. Some services, such as POP3 and IMAP,
have different well known ports defined for the SL
encrypted services. The encrypted ports will be selected
automatically when SL is enabled and no explicit port is
specified. The --sslproto option can be used to select the
SL protocols (default: v2 or v3). The --sslcertck command
line or sslcertck run control file option should be used to
force strict certificate checking - see below.
If SL is not configured, fetchmail will usually opportun-
istically try to use TLS. TLS can be enforced by using
--sslproto "TLS1". TLS connections use the same port as the
unencrypted version of the protocol and negotiate TLS via
special parameter. The --sslcertck command line or sslcertck
run control file option should be used to force strict cer-
tificate checking - see below.
--sslcertck recommended: When connecting to an SL or TLS
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. If the --sslcertck command line option or
sslcertck run control file option is used, fetchmail will
instead abort if any of these checks fail. Use of the
sslcertck or --sslcertck option is advised.
Some SL encrypted servers may request a client side certi-
ficate. A client side public SL certificate and private
SL 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 Certify-
ing Authority. The format for the key files and the certi-
ficate files is that required by the underlying SL
libraries (OpenSL in the general case).
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fetchmail reference manual fetchmail(1)
A word of care about the use of SL: 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:/monkey.org/~dugsong/dsniff/). Use of strict certifi-
cate checking with a certification authority recognized by
server and client, or perhaps of an SH tunnel (see below
for some examples) is preferable if you care seriously about
the security of your mailbox and passwords.
ESMTP AUTH
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
Introducing the daemon mode
In daemon mode, fetchmail puts itself into the background
and runs forever, querying each specified host and then
sleeping for a given polling interval.
Starting the daemon mode
There are several ways to make fetchmail work in daemon
mode. On the command line, --daemon or
-d option runs fetchmail in daemon mode. You
must specify a numeric argument which is a polling interval
in seconds.
Example: 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 15 minutes.
It is also possible to set a polling interval in your
~/.fetchmailrc file by saying 'set daemon ', where
is an integer number of seconds. If you do this,
fetchmail will always start in daemon mode unless you over-
ride it with the command-line option --daemon 0 or -d0.
Only one daemon process is permitted per user; in daemon
mode, fetchmail sets up a per-user lockfile to guarantee
this. (You can however cheat and set the FETCHMAILHOME
environment variable to overcome this setting, but in that
fetchmail Last change: fetchmail 6.3.8 23
fetchmail reference manual fetchmail(1)
case, it is your responsibility to make sure you aren't pol-
ling the same server with two processes at the same time.)
Awakening the background daemon
Normally, calling fetchmail with a daemon in the background
sends a wake-up signal to the daemon and quits without out-
put. The background daemon then starts its next poll cycle
immediately. The wake-up signal, SIGUSR1, can also be sent
manually. The wake-up action also clears any authentication
or multiple timeouts.
Terminating the background daemon
The option --quit will kill a running daemon process instead
of waking it up (if there is no such process, fetchmail will
notify you. If the --quit option appears last on the com-
mand line, fetchmail will kill the running daemon process
and then quit. Otherwise, fetchmail will first kill a run-
ning daemon process and then continue running with the other
options.
Useful options for daemon mode
The -L or --logfile option (keyword:
set logfile) is only effective when fetchmail is detached.
This option allows you to redirect status messages 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 con-
figurations. Note that fetchmail does not detect if the log-
file is rotated, the logfile is only opened once when fetch-
mail starts. You need to restart fetchmail after rotating
the logfile and before compressing it (if applicable).
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 LOGMAIL, and priorities LOGER,
LOGALERT or LOGINFO. 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
option was used.
The -N or --nodetach option suppresses backgrounding and
detachment of the daemon process from its control terminal.
This is useful for debugging or when fetchmail runs as the
child of a supervisor process such as init(8) or Gerrit
Pape's runit. Note that this also causes the logfile option
to be ignored (though perhaps it shouldn't).
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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 fetch-
mail is running in daemon mode, this will be detected at the
beginning of the next poll cycle. When a changed ~/.fetch-
mailrc 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 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. It is also used as destination of undeliverable mail
if the 'bouncemail' global option is off and additionally
for spam-blocked mail if the 'bouncemail' global option is
off and the 'spambounce' global option is on. This option
defaults to 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 as described above to be discarded - this however
is usually a bad idea. See also the description of the
'FETCHMAILUSER' environment variable in the ENVIRONMENT sec-
tion below.
The --nobounce behaves like the "set no bouncemail" global
option, which see.
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 transmis-
sion, 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 fetch-
mail to show progress dots even if the current tty is not
fetchmail Last change: fetchmail 6.3.8 25
fetchmail reference manual fetchmail(1)
stdout (for example logfiles). Fetchmail shows the dots by
default when run in nodetach mode or when daemon mode is not
enabled.
By specifying the --tracepolls option, you can ask fetchmail
to add information to the Received header on the form "pol-
ling {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 'tra-
cepolls'.
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 ack-
nowledged 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 possibil-
ity of error. Some MDAs are 'safe' and reliably return a
nonzero status on any delivery error, even one due to tem-
porary resource limits. The maildrop(1) program is like
this; so are most programs designed as mail transport
agents, such as sendmail(1), including the sendmail wrapper
of Postfix 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 mes-
sages, so fetchmail must treat all messages as new all the
time. But POP2 is obsolete, so this is unlikely.
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A potential POP3 problem might be servers that insert mes-
sages 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. Using UIDL whilst setting fastuidl 0 might
fix this, otherwise, consider switching to IMAP.
Yet another POP3 problem is that if they can't make temp-
files 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. This
isn't the right thing to do, fetchmail should check the UID-
VALIDITY and use UID, but it doesn't do that yet. 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 mes-
sages 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.
According to RFC2821, the correct thing to return in this
situation is 550 "Requested action not taken: mailbox una-
vailable" (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.
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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 mul-
tidropped 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 immedi-
ately 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 global option is on, mail that is spam-
blocked triggers an RFC1892/RFC1894 bounce message informing
the originator that we do not accept mail from it. See also
BUGS.
SMTP/ESMTP EROR 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. See
also BUGS.
THE RUN CONTROL FILE
The preferred way to set up fetchmail is to write a .fetch-
mailrc file in your home directory (you may do this
directly, with a text editor, or indirectly via fetchmail-
conf). When there is a conflict between the command-line
arguments and the arguments in this file, the command-line
arguments take precedence.
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To protect the security of your passwords, your ~/.fetch-
mailrc may not normally have more than 0600 (u=rw,g=,o=)
permissions; fetchmail will complain and exit otherwise
(this check is suppressed when --version is on).
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). Note that quoted strings will also contain line
feed characters if they run across two or more lines, unless
you use a backslash to join lines (see below). 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 backslash escape
sequences (\n for LF, \t for HT, \b for BS, \r for CR, \nnn
for decimal (where nnn cannot start with a 0), \0ooo for
octal, and \xhh for hex) to embed non-printable characters
or string delimiters in strings. In quoted strings, a
backslash at the very end of a line will cause the backslash
itself and the line feed (LF or NL, new line) character to
be ignored, so that you can wrap long strings. Without the
backslash at the line end, the line feed character would
become part of the string.
Warning: while these resemble C-style escape sequences, they
are not the same. fetchmail only supports these eight
styles. C supports more escape sequences that consist of
backslash (\) and a single character, but does not support
decimal codes and does not require the leading 0 in octal
notation. Example: fetchmail interprets \233 the same as
\xE9 (Latin small letter e with acute), where C would inter-
pret \233 as octal 0233 = \x9B (CSI, control sequence intro-
ducer).
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.
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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 short
command-line options are followed by '-' and the appropriate
option letter. If option is only relevant to a single mode
of operation, it is noted as 's' or 'm' for singledrop- or
multidrop-mode, respectively.
Here are the legal global options:
Keyword Opt Mode Function
set daemon -d Set a background poll interval in
seconds.
set postmaster Give the name of the last-resort
mail recipient (default: user run-
ning fetchmail, "postmaster" if
run by the root user)
set bouncemail Direct error mail to the sender
(default)
set no bouncemail Direct error mail to the local
postmaster (as per the 'postmas-
ter' global option above).
set no spambounce Do not bounce spam-blocked mail
(default).
set spambounce Bounce blocked spam-blocked mail
(as per the 'antispam' user
option) back to the destination as
indicated by the 'bouncemail' glo-
bal option. Warning: Do not use
this to bounce spam back to the
sender - most spam is sent with
false sender address and thus this
option hurts innocent bystanders.
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set logfile -L Name of a file to append error and
status messages to.
set idfile -i Name of the file to store UID
lists in.
set syslog Do error logging through sys-
log(3).
set no syslog Turn off error logging through
syslog(3). (default)
set properties String value that is ignored by
fetchmail (may be used by exten-
sion scripts).
Here are the legal server options:
Keyword Opt Mode Function
via Specify DNS name of mailserver,
overriding poll name
proto[col] -p Specify protocol (case insensi-
tive): POP2, POP3, IMAP, APOP,
KPOP
local[domains] m Specify domain(s) to be regarded
as local
port Specify TCP/IP service port
(obsolete, use 'service' instead).
service -P Specify service name (a numeric
value is also allowed and con-
sidered a TCP/IP port number).
auth[enticate] Set authentication type (default
timeout -t Server inactivity timeout in
seconds (default 300)
envelope -E m Specify envelope-address header
name
no envelope m Disable looking for envelope
address
qvirtual -Q m Qmail virtual domain prefix to
remove from user name
aka m 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 m Enable DNS lookup for multidrop
(default)
no dns m Disable DNS lookup for multidrop
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checkalias m Do comparison by IP address for
multidrop
no checkalias m Do comparison by name for mul-
tidrop (default)
uidl -U Force POP3 to use client-side
UIDLs (recommended)
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
principal Set Kerberos principal (only use-
ful with IMAP and kerberos)
esmtpname Set name for RFC2554 authentica-
tion to the ESMTP server.
esmtppassword Set password for RFC2554 authenti-
cation to the ESMTP server.
Here are the legal user options:
Keyword Opt Mode 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 speci-
fied base protocol using SL
encryption
sslcert Specify file for client side pub-
lic SL certificate
sslkey Specify file for client side
private SL key
sslproto Force ssl protocol for connection
folder -r Specify remote folder to query
smtphost -S Specify smtp host(s) to forward to
fetchdomains m 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
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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 (for POP3, uidl is recom-
mended)
flush -F Flush all seen messages before
querying (DANGEROUS)
limitflush Flush all oversized 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 mes-
sages after each poll (IMAP only)
limit -l Set message size limit
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warnings -w Set message size warning interval
batchlimit -b Max # messages to forward in sin-
gle 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 fetch-
mail (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
be preceded by a whitespace-separated number. This number,
if specified, is the number of such headers to skip over
(that is, an argument of 1 selects the second header of the
given type). This is sometime useful for ignoring bogus
envelope headers created by an ISP's local delivery agent or
internal forwards (through mail inspection systems, for
instance).
Keywords Not Corresponding To Option Switches
The 'folder' and 'smtphost' options (unlike their command-
line equivalents) can take a space- or comma-separated list
of names following them.
All options correspond to the obvious command-line argu-
ments, except the following: 'via', 'interval', 'aka', 'is',
'to', 'dns'/'no dns', 'checkalias'/'no checkalias', 'pass-
word', 'preconnect', 'postconnect', 'localdomains',
'stripcr'/'no stripcr', 'forcecr'/'no forcecr',
'pass8bits'/'no pass8bits' 'dropstatus/no dropstatus',
'dropdelivered/no dropdelivered', 'mimedecode/no
mimedecode', 'no idle', and 'no envelope'.
The 'via' option is for if you want to have more than one
configuration pointing at the same site. If it is present,
the string argument will be taken as the actual DNS name of
the mailserver host to query. This will override the argu-
ment of poll, which can then simply be a distinct label for
the configuration (e.g. what you would give on the command
line to explicitly query this host).
The 'interval' option (which takes a numeric argument)
allows you to poll a server less frequently than the basic
poll interval. If you say 'interval N' the server this
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fetchmail reference manual fetchmail(1)
option is attached to will only be queried every N poll
intervals.
Singledrop vs. Multidrop options
Please ensure you read the section titled THE USE AND ABUSE
OF MULTIDROP if you intend to use multidrop mode.
The 'is' or 'to' keywords associate the following local
(client) name(s) (or server-name to client-name mappings
separated by =) with the mailserver user name in the entry.
If an is/to list has '*' as its last name, unrecognized
names are simply passed through. Note that until fetchmail
version 6.3.4 inclusively, these lists could only contain
local parts of user names (fetchmail would only look at the
part before the @ sign). fetchmail versions 6.3.5 and newer
support full addresses on the left hand side of these map-
pings, and they take precedence over any 'localdomains',
'aka', 'via' or similar mappings.
A single local name can be used to support redirecting your
mail when your username on the client machine is different
from your name on the mailserver. When there is only a sin-
gle local name, mail is forwarded to that local username
regardless of the message's Received, To, Cc, and Bcc
headers. In this case, fetchmail never does DNS lookups.
When there is more than one local name (or name mapping),
fetchmail looks at the envelope header, if configured, and
otherwise at the Received, To, Cc, and Bcc headers of
retrieved mail (this is 'multidrop mode'). It looks for
addresses with hostname parts that match your poll name or
your 'via', 'aka' or 'localdomains' options, and usually
also for hostname parts which DNS tells it are aliases of
the mailserver. See the discussion of 'dns', 'checkalias',
'localdomains', and 'aka' for details on how matching
addresses are handled.
If fetchmail cannot match any mailserver usernames or local-
domain addresses, the mail will be bounced. Normally it
will be bounced to the sender, but if the 'bouncemail' glo-
bal option is off, the mail will go to the local postmaster
instead. (see the 'postmaster' global option). See also
BUGS.
The 'dns' option (normally on) controls the way addresses
from multidrop mailboxes are checked. On, it enables logic
to check each host address that does not match an 'aka' or
'localdomains' declaration by looking it up with DNS. When
a mailserver username is recognized attached to a matching
hostname part, its local mapping is added to the list of
local recipients.
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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. When such a server is polled, checks to extract the
envelope address fail, and fetchmail reverts to delivery
using the To/Cc/Bcc headers (See below 'Header vs. Envelope
addresses'). Specifying this option instructs fetchmail to
retrieve all the IP addresses associated with both the poll
name and the name used by the remote MTA and to do a com-
parison of the IP addresses. This comes in handy in situa-
tions where the remote server undergoes frequent canonical
name changes, that would otherwise require 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 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 fetchmail, 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
hostname netaxs.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
domains which fetchmail should consider local. When fetch-
mail is parsing 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 previ-
ously set by 'envelope'. If you set 'no envelope' in the
defaults entry it is possible to undo that in individual
entries by using 'envelope '. 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 com-
mand to be executed just before each time fetchmail estab-
lishes a mailserver connection. This may be useful if you
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fetchmail reference manual fetchmail(1)
are attempting to set up secure POP connections with the aid
of ssh(1). 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, fetchmail 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, fetchmail is forced to
declare BODY=8BITMIME to any ESMTP-capable listener. If the
listener is 8-bit-clean (as all the major ones now are) the
right thing will probably result.
The 'dropstatus' option controls whether nonempty Status and
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 whether Delivered-To
headers will be kept in fetched mail (the default) or dis-
carded. These headers are added by Qmail and Postfix mail-
servers 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
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fetchmail reference manual fetchmail(1)
into pure 8-bit data. If you are delivering mail to an
ESMTP-capable, 8-bit-clean listener (that includes all of
the major MTAs like sendmail), then 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 intended to be used with IMAP servers
supporting the RFC2177 IDLE command extension, but does not
strictly require it. 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 IDLE is not supported, fetchmail will
simulate it by periodically issuing NOP. If you need to
poll a link frequently, IDLE can save bandwidth by eliminat-
ing 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 polls 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.
Miscellaneous Run Control Options
The words 'here' and 'there' have useful English-like signi-
ficance. 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' key-
word are:
auto (or AUTO) (legacy, to be removed from future release)
pop2 (or POP2) (legacy, to be removed from future release)
pop3 (or POP3)
sdps (or SDPS)
imap (or IMAP)
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apop (or APOP)
kpop (or KPOP)
Legal authentication types are 'any', 'password', 'ker-
beros', 'kerberosv4', 'kerberosv5' and 'gssapi',
'cram-md5', 'otp', 'msn' (only for POP3), 'ntlm', 'ssh',
'external' (only IMAP). The 'password' type specifies
authentication by normal transmission of a password (the
password may be plain text or subject to protocol-specific
encryption as in CRAM-MD5); '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 GSAPI 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 overrid-
den by later options.
There are some global option statements: 'set logfile' fol-
lowed by a string sets the same global specified by --log-
file. A command-line --logfile option will override this.
Note that --logfile is only effective if fetchmail detaches
itself from the terminal. 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).
DEBUGING FETCHMAIL
Fetchmail crashing
There are various ways in that fetchmail may "crash", i. e.
stop operation suddenly and unexpectedly. A "crash" usually
refers to an error condition that the software did not han-
dle by itself. A well-known failure mode is the "segmenta-
tion fault" or "signal 11" or "SIGSEGV" or just "segfault"
for short. These can be caused by hardware or by software
problems. Software-induced segfaults can usually be repro-
duced easily and in the same place, whereas hardware-induced
segfaults can go away if the computer is rebooted, or
powered off for a few hours, and can happen in random loca-
tions even if you use the software the same way.
For solving hardware-induced segfaults, find the faulty com-
ponent and repair or replace it.
may help you with details.
For solving software-induced segfaults, the developers may
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fetchmail reference manual fetchmail(1)
need a "stack backtrace".
Enabling fetchmail core dumps
By default, fetchmail suppresses core dumps as these might
contain passwords and other sensitive information. For
debugging fetchmail crashes, obtaining a "stack backtrace"
from a core dump is often the quickest way to solve the
problem, and when posting your problem on a mailing list,
the developers may ask you for a "backtrace".
1. To get useful backtraces, fetchmail needs to be installed
without getting stripped of its compilation symbols. Unfor-
tunately, most binary packages that are installed are
stripped, and core files from symbol-stripped programs are
worthless. So you may need to recompile fetchmail. On many
systems, you can type
file `which fetchmail`
to find out if fetchmail was symbol-stripped or not. If
yours was unstripped, fine, proceed, if it was stripped, you
need to recompile the source code first. You do not usually
need to install fetchmail in order to debug it.
2. The shell environment that starts fetchmail needs to
enable core dumps. The key is the "maximum core (file) size"
that can usually be configured with a tool named "limit" or
"ulimit". See the documentation for your shell for details.
In the popular bash shell, "ulimit -Sc unlimited" will allow
the core dump.
3. You need to tell fetchmail, too, to allow core dumps. To
do this, run fetchmail with the -d0 -v options. It is often
easier to also add --nosyslog -N as well.
Finally, you need to reproduce the crash. You can just start
fetchmail from the directory where you compiled it by typing
./fetchmail, so the complete command line will start with
./fetchmail -Nvd0 --nosyslog and perhaps list your other
options.
After the crash, run your debugger to obtain the core dump.
The debugger will often be GNU GDB, you can then type
(adjust paths as necessary) gdb ./fetchmail fetchmail.core
and then, after GDB has started up and read all its files,
type backtrace full, save the output (copy & paste will do,
the backtrace will be read by a human) and then type quit to
leave gdb. Note: on some systems, the core files have dif-
ferent names, they might contain a number instead of the
program name, or number and name, but it will usually have
"core" as part of their name.
fetchmail Last change: fetchmail 6.3.8 40
fetchmail reference manual fetchmail(1)
INTERACTION WITH RFC 822
When trying to determine the originating address of a mes-
sage, 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 mes-
sages 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 fol-
lows: First, fetchmail looks for the header specified by
the 'envelope' option in order to determine the local reci-
pient 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 exist, they should contain the
final recipients and have precedence over their To:/Cc:/Bcc:
counterparts. If the Resent-* lines don'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 origi-
nal copy of the mail.)
CONFIGURATION EXAMPLES
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 PASWORD
Example:
poll pop.provider.net protocol pop3 username "jsmith" password "secret1"
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fetchmail reference manual fetchmail(1)
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 signi-
ficantly 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 descrip-
tions. 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 descrip-
tion, 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
fetchmail Last change: fetchmail 6.3.8 42
fetchmail reference manual fetchmail(1)
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 multidrop
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 multidrop 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'.
Note that fetchmail, until version 6.3.4, did NOT allow full
user@domain specifications here, these would never match.
Fetchmail 6.3.5 and newer support user@domain specifications
on the left-hand side of a user mapping.
Here's an example of another kind of multidrop connection:
poll pop.provider.net localdomains loonytoons.org toons.org
envelope X-Envelope-To
user maildrop with pass secret1 to * here
This also says that the mailbox of account 'maildrop' on the
server is a multidrop box. It tells fetchmail that any
address in the loonytoons.org or toons.org domains (includ-
ing sub-domain 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;
user esr is esr here
THE USE AND ABUSE OF MULTIDROP
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
fetchmail Last change: fetchmail 6.3.8 43
fetchmail reference manual fetchmail(1)
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.
Header vs. Envelope addresses
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 headers - the Bcc is not available at the receiving
end). This 'envelope address' is the address you need in
order to reroute mail properly.
Sometimes fetchmail can deduce the envelope address. If the
mailserver MTA is sendmail 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'.
As a better alternative, 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-Original-To', 'Delivered-To' or '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, so
the upstream must store one copy of the message per reci-
pient to avoid becoming a privacy problem.
Postfix, since version 2.0, writes an X-Original-To: header
which contains a copy of the envelope as it was received.
Qmail and Postfix generally write a 'Delivered-To' header
upon delivering the message to the mail spool and use it to
avoid mail loops. Qmail virtual domains however will prefix
the user name with a string that normally matches the user's
domain. To remove this prefix you can use the -Q or 'qvir-
tual' option.
Sometimes, unfortunately, neither of these methods works.
That is the point when you should contact your ISP and ask
them to provide such an envelope header, and you should not
use multidrop in this situation. When they all fail, fetch-
mail must fall back on the contents of To/Cc headers (Bcc
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fetchmail reference manual fetchmail(1)
headers are not available - see below) to try to determine
recipient addressees -- and these are unreliable. In par-
ticular, mailing-list software often ships mail with only
the list broadcast address in the To header.
Note that a future version of
When fetchmail 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 without proper
envelope information.
A related problem is that when you blind-copy a mail mes-
sage, the Bcc information is carried only as envelope
address (it's removed from the headers by the sending mail
server, so fetchmail can see it only if there is an X-
Envelope-To header). Thus, blind-copying to someone who
gets mail over a fetchmail multidrop link will fail unless
the the mailserver host routinely writes X-Envelope-To or an
equivalent header into messages in your maildrop.
In conclusion, mailing lists and Bcc'd mail can only work if
the server you're fetching from (1) stores one copy of the
message per recipient in your domain and (2) records the
envelope information in a special header (X-Original-To,
Delivered-To, X-Envelope-To).
Good Ways To Use Multidrop Mailboxes
Multiple local names can be used to administer a mailing
list from the client side of a fetchmail collection. Sup-
pose 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 expan-
sion 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
fetchmail Last change: fetchmail 6.3.8 45
fetchmail reference manual fetchmail(1)
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 fetchmail, but the
program has no way to know that that's actually the right
thing.
Bad Ways To Abuse Multidrop Mailboxes
Multidrop mailboxes and fetchmail 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 fetchmail can deduce an
envelope address, such mail will only go to the account run-
ning fetchmail (probably root). Also, blind-copied users
are very likely never to see their mail at all.
If you're tempted to use fetchmail to retrieve mail for mul-
tiple 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 UCP 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.
Speeding Up Multidrop Checking
Normally, when multiple users are declared fetchmail
extracts recipient addresses as described above and checks
each host part with DNS to see if it's an alias of the mail-
server. If so, the name mappings described in the "to ...
here" declaration are done and the mail locally delivered.
This is a convenient but also slow 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 all DNS aliases of the mailserver (and all MX
names pointing at it - note this may change in a future ver-
sion) you can declare 'no dns' to suppress DNS lookups
entirely and only match against the aka list.
fetchmail Last change: fetchmail 6.3.8 46
fetchmail reference manual fetchmail(1)
SOCKS
Support for socks4/5 is a compile time configuration option.
Once compiled in, fetchmail will always use the socks
libraries and configuration on your system, there are no
run-time switches in fetchmail - but you can still configure
SOCKS: you can specify which SOCKS configuration file is
used in the SOCKSCONF environment variable.
For instance, if you wanted to bypass the SOCKS proxy alto-
gether and have fetchmail connect directly, you could just
pass SOCKSCONF=/dev/null in the environment, for example
(add your usual command line options - if any - to the end
of this line):
env SOCKSCONF=/dev/null fetchmail
EXIT CODES
To facilitate the use of fetchmail in shell scripts, an
exit status code is returned to give an indication of what
occurred during a given connection.
The exit codes returned by fetchmail are as follows:
0 One or more messages were successfully retrieved (or,
if the -c option was selected, were found waiting but
not retrieved).
1 There was no mail awaiting retrieval. (There may have
been old mail still on the server but not selected for
retrieval.)
2 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.
3 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 fetch-
mail under circumstances where it did not have standard
input attached to a terminal and could not prompt for a
missing password.
4 Some sort of fatal protocol error was detected.
5 There was a syntax error in the arguments to fetchmail.
6 The run control file had bad permissions.
fetchmail Last change: fetchmail 6.3.8 47
fetchmail reference manual fetchmail(1)
7 There was an error condition reported by the server.
Can also fire if fetchmail timed out while waiting for
the server.
8 Client-side exclusion error. This means fetchmail
either found another copy of itself already running, or
failed in such a way that it isn't sure whether another
copy is running.
9 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 con-
taining the word "lock".
10 The fetchmail run failed while trying to do an SMTP
port open or transaction.
11 Fatal DNS error. Fetchmail encountered an error while
performing a 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.
23 Internal error. You should see a message on standard
error with details.
24 - 26, 28, 29
These are internal codes and should not appear exter-
nally.
When fetchmail 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.
FILES
~/.fetchmailrc
default run control file
~/.fetchids
default location of file associating hosts with last
message IDs seen (used only with newer RFC1939-
compliant POP3 servers supporting the UIDL command).
fetchmail Last change: fetchmail 6.3.8 48
fetchmail reference manual fetchmail(1)
~/.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 prompt-
ing 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).
ENVIRONMENT
FETCHMAILUSER: 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. Other-
wise, 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).
FETCHMAILHOME: If the environment variable FETCHMAILHOME is
set to a valid and existing directory name, fetchmail will
read $FETCHMAILHOME/fetchmailrc (the dot is missing in this
case), $FETCHMAILHOME/.fetchids and
$FETCHMAILHOME/.fetchmail.pid rather than from the user's
home directory. The .netrc file is always looked for in the
the invoking user's home directory regardless of
FETCHMAILHOME's setting.
HOMETC: If the HOMETC variable is set, fetchmail will
read $HOMETC/.fetchmailrc instead of ~/.fetchmailrc.
If HOMETC and FETCHMAILHOME are both set, HOMETC will be
ignored.
SOCKSCONF: (only if SOCKS support is compiled in) this
variable is used by the socks library to find out which con-
figuration file it should read. Set this to /dev/null to
bypass the SOCKS proxy.
SIGNALS
If a fetchmail daemon is running as root, SIGUSR1 wakes it
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fetchmail reference manual fetchmail(1)
up from its sleep phase and forces a poll of all non-skipped
servers. For compatibility reasons, SIGHUP can also be used
in 6.3.X but may not be available in future fetchmail ver-
sions.
If fetchmail 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 fetchmail in foreground while a background fetchmail
is running will do whichever of these is appropriate to wake
it up.
BUGS AND KNOWN PROBLEMS
Please check the NEWS file that shipped with fetchmail for
more known bugs than those listed here.
Fetchmail cannot handle user names that contain blanks after
a "@" character, for instance "demonstr@ti on". These are
rather uncommon and only hurt when using UID-based --keep
setups, so the 6.3.X versions of fetchmail won't be fixed.
The assumptions that the DNS and in particular the check-
alias options make are not often sustainable. For instance,
it has become uncommon for an MX server to be a POP3 or IMAP
server at the same time. Therefore the MX lookups may go
away in a future release.
The mda and plugin options interact badly. In order to col-
lect 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 --interface option does not support IPv6 and it is
doubtful if it ever will, since there is no portable way to
query interface IPv6 addresses.
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.
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
fetchmail Last change: fetchmail 6.3.8 50
fetchmail reference manual fetchmail(1)
might be snaffled with a packet sniffer or more sophisti-
cated monitoring software. Under Linux and FreeBSD, the
--interface option can be used to restrict polling to avai-
lability 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 ssh(1) tunnelling to not
only shroud your passwords but encrypt the entire conversa-
tion.
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 max-
imum 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 bounces due to errors or
spam-blocking and spam bounces requires that port 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, 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 'principal' option only handles Kerberos IV, not V.
Interactively entered passwords are truncated after 63 char-
acters. If you really need to use a longer password, you
will have to use a configuration file.
A backslash as the last character of a configuration file
will be flagged as a syntax error rather than ignored.
The BSMTP error handling is virtually nonexistent and may
leave broken messages behind.
Send comments, bug reports, gripes, and the like to the
fetchmail-devel list . An
HTML FAQ is available at the fetchmail home page; surf to
http:/fetchmail.berlios.de/ or do a W search for pages
with 'fetchmail' in their titles.
fetchmail Last change: fetchmail 6.3.8 51
fetchmail reference manual fetchmail(1)
AUTHOR
Fetchmail is currently maintained by Matthias Andree and Rob
Funk with major assistance from Sunil Shetye (for code) and
Rob MacGregor (for the mailing lists).
Most of the code is from Eric S. Raymond
. Too many other people to name here
have contributed code and patches.
This program is descended from and replaces popclient, by
Carl Harris ; the internals have become
quite different, but some of its interface design is
directly traceable to that ancestral program.
This manual page has been improved by R. Hannes Beinert and
H['e]ctor Garc['i]a.
SEE ALSO
mutt(1), elm(1), mail(1), sendmail(8), popd(8), imapd(8),
netrc(5)
The fetchmail home page:
The maildrop home page:
APLICABLE STANDARDS
Note that this list is just a collection of references and
not a statement as to the actual protocol conformance or
requirements in fetchmail.
SMTP/ESMTP:
RFC 821, RFC 2821, RFC 1869, RFC 1652, RFC 1870, RFC
1983, RFC 1985, RFC 2554.
mail:
RFC 822, RFC 2822, RFC 1123, RFC 1892, RFC 1894.
POP2:
RFC 937
POP3:
RFC 1081, RFC 1225, RFC 1460, RFC 1725, RFC 1734, RFC
1939, RFC 1957, RFC 2195, RFC 2449.
APOP:
RFC 1939.
RPOP:
RFC 1081, RFC 1225.
fetchmail Last change: fetchmail 6.3.8 52
fetchmail reference manual fetchmail(1)
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.
GSAPI:
RFC 1508.
TLS: RFC 2595.
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWfetchmail
Interface Stability Committed
NOTES
Source for fetchmail is available on http:/opensolaris.org.
fetchmail Last change: fetchmail 6.3.8 53
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