procmail(1)
NAME
procmail - autonomous mail processor
SYNOPSIS
procmail [-ptoY] [-f fromwhom]
[parameter=value | rcfile] ...
procmail [-toY] [-f fromwhom] [-a argument] ...
-d recipient ...
procmail [-ptY] -m [parameter=value] ... rcfile
[argument] ...
procmail -v
DESCRIPTION
For a quick start, see NOTES at the end. Procmail should be invoked automatically over the .forward file mechanism as soon as mail arrives. Alternatively, when installed by a system administrator, it can be invoked from within the mailer immediately. When invoked, it first sets some environment variables to default values, reads the mail message from stdin until an EOF, separates the body from the header, and then, if no command line arguments are present, it starts to look for a file named $HOME/.procmailrc. According to the processing recipes in this file, the mail message that just arrived gets distributed into the right folder (and more). If no rcfile is found, or processing of the rcfile falls off the end, procmail will store the mail in the default system mailbox. If no rcfiles and no -p have been specified on the command line, procmail will, prior to reading $HOME/.procmailrc, interpret commands from /etc/procmailrc (if present). Care must be taken when creating /etc/procmailrc, because, if circumstances permit, it will be executed with root privileges (contrary to the $HOME/.procmailrc file of course). If running suid root or with root privileges, procmail will be able to perform as a functionally enhanced, backwards compatible mail delivery agent. Procmail can also be used as a general purpose mail filter, i.e., provisions have been made to enable procmail to be invoked in a special sendmail rule. The rcfile format is described in detail in the procmailrc(5) man page. The weighted scoring technique is described in detail in the procmailsc(5) man page. Examples for rcfile recipes can be looked up in the procmailex(5) man page. Signals TERMINATE Terminate prematurely and requeue the mail. HANGUP Terminate prematurely and bounce the mail. INTERRUPT Terminate prematurely and bounce the mail. QUIT Terminate prematurely and silently lose the mail. ALARM Force a timeout (see TIMEOUT). USR1 Equivalent to a VERBOSE=off. USR2 Equivalent to a VERBOSE=on.
OPTIONS
-v Procmail will print its version number, display its compile time
configuration and exit.
-p Preserve any old environment. Normally procmail clears the
environment upon startup, except for the value of TZ. However, in
any case: any default values will override any preexisting
environment variables, i.e., procmail will not pay any attention
to any predefined environment variables, it will happily overwrite
them with its own defaults. For the list of environment variables
that procmail will preset see the procmailrc(5) man page. If both
-p and -m are specified, the list of preset environment variables
shrinks to just: LOGNAME, HOME, SHELL, ORGMAIL and MAILDIR.
-t Make procmail fail softly, i.e., if procmail cannot deliver the
mail to any of the destinations you gave, the mail will not
bounce, but will return to the mailqueue. Another delivery-
attempt will be made at some time in the future.
-f fromwhom
Causes procmail to regenerate the leading `From ' line with
fromwhom as the sender (instead of -f one could use the alternate
and obsolete -r). If fromwhom consists merely of a single `-',
then procmail will only update the timestamp on the `From ' line
(if present, if not, it will generate a new one).
-o Instead of allowing anyone to generate `From ' lines, simply
override the fakes.
-Y Assume traditional Berkeley mailbox format, ignore any Content-
Length: fields.
-a argument
This will set $1 to be equal to argument. Each succeeding -a
argument will set the next number variable ($2, $3, etc). It can
be used to pass meta information along to procmail. This is
typically done by passing along the $@x information from the
sendmail mailer rule.
-d recipient ...
This turns on explicit delivery mode, delivery will be to the
local user recipient. This, of course, only is possible if
procmail has root privileges (or if procmail is already running
with the recipient's euid and egid). Procmail will setuid to the
intended recipients and delivers the mail as if it were invoked by
the recipient with no arguments (i.e., if no rcfile is found,
delivery is like ordinary mail). This option is incompatible with
-p.
-m Turns procmail into a general purpose mail filter. In this mode
one rcfile must be specified on the command line. After the
rcfile, procmail will accept an unlimited number of arguments. If
the rcfile is an absolute path starting with /etc/procmailrcs/
without backward references (i.e. the parent directory cannot be
mentioned) procmail will, only if no security violations are
found, take on the identity of the owner of the rcfile (or
symbolic link). For some advanced usage of this option you should
look in the EXAMPLES section below.
ARGUMENTS
Any arguments containing an '=' are considered to be environment variable assignments, they will all be evaluated after the default values have been assigned and before the first rcfile is opened. Any other arguments are presumed to be rcfile paths (either absolute, or if they start with `./' relative to the current directory; any other relative path is relative to $HOME, unless the -m option has been given, in which case all relative paths are relative to the current directory); procmail will start with the first one it finds on the command line. The following ones will only be parsed if the preceding ones have a not matching HOST-directive entry, or in case they should not exist. If no rcfiles are specified, it looks for $HOME/.procmailrc. If not even that can be found, processing will continue according to the default settings of the environment variables and the ones specified on the command line.
EXAMPLES
Examples for rcfile recipes can be looked up in the procmailex(5) man page. A small sample rcfile can be found in the NOTES section below. Skip the rest of this EXAMPLES section unless you are a system administrator who is vaguely familiar with sendmail.cf syntax. The -m option is typically used when procmail is called from within a rule in the sendmail.cf file. In order to be able to do this it is convenient to create an extra `procmail' mailer in your sendmail.cf file (in addition to the perhaps already present `local' mailer that starts up procmail). To create such a `procmail' mailer I'd suggest something like: Mprocmail, P=/usr/bin/procmail, F=mSDFMhun, S=11, R=21, A=procmail -m $h $g $u This enables you to use rules like the following (most likely in ruleset 0) to filter mail through the procmail mailer (please note the leading tab to continue the rule, and the tab to separate the comments): R$*<@some.where>$* $#procmail $@/etc/procmailrcs/some.rc $:$1@some.where.procmail$2 R$*<@$*.procmail>$* $1<@$2>$3 Already filtered, map back And /etc/procmailrcs/some.rc could be as simple as: SENDER = "<$1>" # fix for empty sender addresses SHIFT = 1 # remove it from $@ :0 # sink all junk mail * ^Subject:.*junk /dev/null :0 w # pass along all other mail ! -oi -f "$SENDER" "$@" Do watch out when sending mail from within the /etc/procmailrcs/some.rc file, if you send mail to addresses which match the first rule again, you could be creating an endless mail loop.
FILES
/etc/passwd to set the recipient's LOGNAME, HOME and SHELL
variable defaults
/var/mail/$LOGNAME system mailbox; both the system mailbox and the
immediate directory it is in will be created
every time procmail starts and either one is not
present
/etc/procmailrc initial global rcfile
/etc/procmailrcs/ special privileges path for rcfiles
$HOME/.procmailrc default rcfile
/var/mail/$LOGNAME.lock
lockfile for the system mailbox (not
automatically used by procmail, unless $DEFAULT
equals /var/mail/$LOGNAME and procmail is
delivering to $DEFAULT)
/usr/sbin/sendmail default mail forwarder
_????`hostname` temporary `unique' zero-length files created by
procmail
SEE ALSO
procmailrc(5), procmailsc(5), procmailex(5), sh(1), csh(1), mail(1), mailx(1), uucp(1), aliases(5), sendmail(8), egrep(1), grep(1), biff(1), comsat(8), lockfile(1), formail(1), cron(1)
DIAGNOSTICS
Autoforwarding mailbox found
The system mailbox had its suid or sgid bit set,
procmail terminates with EX_NOUSER assuming that
this mailbox must not be delivered to.
Bad substitution of "x"
Not a valid environment variable name specified.
Closing brace unexpected
There was no corresponding opening brace
(nesting block).
Conflicting options Not all option combinations are useful
Conflicting x suppressed
Flag x is not compatible with some other flag on
this recipe.
Couldn't create "x" The system mailbox was missing and could
not/will not be created.
Couldn't create maildir part "x"
The maildir folder "x" is missing one or more
required subdirectories and procmail could not
create them.
Couldn't create or rename temp file "x"
An error occurred in the mechanics of
delivering to the directory folder "x".
Couldn't determine implicit lockfile from "x"
There were no `>>' redirectors to be found,
using simply `$LOCKEXT' as locallockfile.
Couldn't read "x" Procmail was unable to open an rcfile or it was
not a regular file, or procmail couldn't open an
MH directory to find the highest numbered file.
Couldn't unlock "x" Lockfile was already gone, or write permission
to the directory where the lockfile is has been
denied.
Deadlock attempted on "x"
The locallockfile specified on this recipe is
equal to a still active $LOCKFILE.
Denying special privileges for "x"
Procmail will not take on the identity that
comes with the rcfile because a security
violation was found (e.g. -p or variable
assignments on the command line) or procmail had
insufficient privileges to do so.
Descriptor "x" was not open
As procmail was started, stdin, stdout or stderr
was not connected (possibly an attempt to
subvert security)
Enforcing stricter permissions on "x"
The system mailbox of the recipient was found to
be unsecured, procmail secured it.
Error while writing to "x"
Nonexistent subdirectory, no write permission,
pipe died or disk full.
Exceeded LINEBUF Buffer overflow detected, LINEBUF was too small,
PROCMAIL_OVERFLOW has been set.
MAILDIR is not an absolute path
MAILDIR path too long
ORGMAIL is not an absolute path
ORGMAIL path too long
default rcfile is not an absolute path
default rcfile path too long
The specified item's full path, when expanded,
was longer than LINEBUF or didn't start with a
file separator.
Excessive output quenched from "x"
The program or filter "x" tried to produce too
much output for the current LINEBUF, the rest
was discarded and PROCMAIL_OVERFLOW has been
set.
Extraneous x ignored The action line or other flags on this recipe
makes flag x meaningless.
Failed forking "x" Process table is full (and NORESRETRY has been
exhausted).
Failed to execute "x" Program not in path, or not executable.
Forced unlock denied on "x"
No write permission in the directory where
lockfile "x" resides, or more than one procmail
trying to force a lock at exactly the same time.
Forcing lock on "x" Lockfile "x" is going to be removed by force
because of a timeout (see also: LOCKTIMEOUT).
Incomplete recipe The start of a recipe was found, but it stranded
in an EOF.
Insufficient privileges
Procmail either needs root privileges, or must
have the right (e)uid and (e)gid to run in
delivery mode. The mail will bounce.
Invalid regexp "x" The regular expression "x" contains errors (most
likely some missing or extraneous parens).
Kernel-lock failed While trying to use the kernel-supported locking
calls, one of them failed (usually indicates an
OS error), procmail ignores this error and
proceeds.
Kernel-unlock failed See above.
Lock failure on "x" Can only occur if you specify some real weird
(and illegal) lockfilenames or if the lockfile
could not be created because of insufficient
permissions or nonexistent subdirectories.
Lost "x" Procmail tried to clone itself but could not
find back rcfile "x" (it either got removed or
it was a relative path and you changed directory
since procmail opened it last time).
Missing action The current recipe was found to be incomplete.
Missing closing brace A nesting block was started, but never finished.
Missing name The -f option needs an extra argument.
Missing argument You specified the -a option but forgot the
argument.
Missing rcfile You specified the -m option, procmail expects
the name of an rcfile as argument.
Missing recipient You specified the -d option or called procmail
under a different name, it expects one or more
recipients as arguments.
No space left to finish writing "x"
The filesystem containing "x" does not have
enough free space to permit delivery of the
message to the file.
Out of memory The system is out of swap space (and NORESRETRY
has been exhausted).
Processing continued The unrecognised options on the command line are
ignored, proceeding as usual.
Program failure (nnn) of "x"
Program that was started by procmail returned
nnn instead of EXIT_SUCCESS (=0); if nnn is
negative, then this is the signal the program
died on.
Quota exceeded while writing "x"
The filesize quota for the recipient on the
filesystem containing "x" does not permit
delivering the message to the file.
Renaming bogus "x" into "x"
The system mailbox of the recipient was found to
be bogus, procmail performed evasive actions.
Rescue of unfiltered data succeeded/failed
A filter returned unsuccessfully, procmail tried
to get back the original text.
Skipped: "x" Couldn't do anything with "x" in the rcfile
(syntax error), ignoring it.
Suspicious rcfile "x" The owner of the rcfile was not the recipient or
root, the file was world writable, or the
directory that contained it was world writable,
or this was the default rcfile
($HOME/.procmailrc) and either it was group
writable or the directory that contained it was
group writable (the rcfile was not used).
Terminating prematurely whilst waiting for ...
Procmail received a signal while it was waiting
for ...
Timeout, terminating "x"
Timeout has occurred on program or filter "x".
Timeout, was waiting for "x"
Timeout has occurred on program, filter or file
"x". If it was a program or filter, then it
didn't seem to be running anymore.
Truncated file to former size
The file could not be delivered to successfully,
so the file was truncated to its former size.
Truncating "x" and retrying lock
"x" does not seem to be a valid filename or the
file is not empty.
Unable to treat as directory "x"
Either the suffix on "x" would indicate that it
should be an MH or maildir folder, or it was
listed as an second folder into which to link,
but it already exists and is not a directory.
Unexpected EOL Missing closing quote, or trying to escape EOF.
Unknown user "x" The specified recipient does not have a
corresponding uid.
EXTENDED DIAGNOSTICS
Extended diagnostics can be turned on and off through setting the
VERBOSE variable.
[pid] time & date Procmail's pid and a timestamp. Generated
whenever procmail logs a diagnostic and at least
a second has elapsed since the last timestamp.
Acquiring kernel-lock Procmail now tries to kernel-lock the most
recently opened file (descriptor).
Assigning "x" Environment variable assignment.
Assuming identity of the recipient, VERBOSE=off
Dropping all privileges (if any), implicitly
turns off extended diagnostics.
Bypassed locking "x" The mail spool directory was not accessible to
procmail, it relied solely on kernel locks.
Executing "x" Starting program "x". If it is started by
procmail directly (without an intermediate
shell), procmail will show where it separated
the arguments by inserting commas.
HOST mismatched "x" This host was called "x", HOST contained
something else.
Locking "x" Creating lockfile "x".
Linking to "x" Creating a hardlink between directory folders.
Match on "x" Condition matched.
Matched "x" Assigned "x" to MATCH.
No match on "x" Condition didn't match, recipe skipped.
Non-zero exitcode (nnn) by "x"
Program that was started by procmail as a
condition or as the action of a recipe with the
`W' flag returned nnn instead of EXIT_SUCCESS
(=0); the usage indicates that this is not an
entirely unexpected condition.
Notified comsat: "$LOGNAME@offset:file"
Sent comsat/biff a notice that mail arrived for
user $LOGNAME at `offset' in `file'.
Opening "x" Opening file "x" for appending.
Rcfile: "x" Rcfile changed to "x".
Reiterating kernel-lock
While attempting several locking methods, one of
these failed. Procmail will reiterate until
they all succeed in rapid succession.
Score: added newtotal "x"
This condition scored `added' points, which
resulted in a `newtotal' score.
Unlocking "x" Removing lockfile "x" again.
WARNINGS
You should create a shell script that uses lockfile(1) before invoking your mail shell on any mailbox file other than the system mailbox (unless of course, your mail shell uses the same lockfiles (local or global) you specified in your rcfile). In the unlikely event that you absolutely need to kill procmail before it has finished, first try and use the regular kill command (i.e., not kill -9, see the subsection Signals for suggestions), otherwise some lockfiles might not get removed. Beware when using the -t option, if procmail repeatedly is unable to deliver the mail (e.g., due to an incorrect rcfile), the system mailqueue could fill up. This could aggravate both the local postmaster and other users. The /etc/procmailrc file might be executed with root privileges, so be very careful of what you put in it. SHELL will be equal to that of the current recipient, so if procmail has to invoke the shell, you'd better set it to some safe value first. See also: DROPPRIVS. Keep in mind that if chown(1) is permitted on files in /etc/procmailrcs/, that they can be chowned to root (or anyone else) by their current owners. For maximum security, make sure this directory is executable to root only. Procmail is not the proper tool for sharing one mailbox among many users, such as when you have one POP account for all mail to your domain. It can be done if you manage to configure your MTA to add some headers with the envelope recipient data in order to tell Procmail who a message is for, but this is usually not the right thing to do. Perhaps you want to investigate if your MTA offers `virtual user tables', or check out the `multidrop' facility of Fetchmail.
BUGS
After removing a lockfile by force, procmail waits $SUSPEND seconds before creating a new lockfile so that another process that decides to remove the stale lockfile will not remove the newly created lock by mistake. Procmail uses the regular TERMINATE signal to terminate any runaway filter, but it does not check if the filter responds to that signal and it only sends it to the filter itself, not to any of the filter's children. A continued Content-Length: field is not handled correctly. The embedded newlines in a continued header should be skipped when matching instead of being treated as a single space as they are now.
MISCELLANEOUS
If there is an existing Content-Length: field in the header of the mail
and the -Y option is not specified, procmail will trim the field to
report the correct size. Procmail does not change the fieldwidth.
If there is no Content-Length: field or the -Y option has been
specified and procmail appends to regular mailfolders, any lines in the
body of the message that look like postmarks are prepended with `>'
(disarms bogus mailheaders). The regular expression that is used to
search for these postmarks is:
`\nFrom '
If the destination name used in explicit delivery mode is not in
/etc/passwd, procmail will proceed as if explicit delivery mode was not
in effect. If not in explicit delivery mode and should the uid
procmail is running under, have no corresponding /etc/passwd entry,
then HOME will default to /, LOGNAME will default to #uid, SHELL will
default to /bin/sh, and ORGMAIL will default to /tmp/dead.letter.
When in explicit delivery mode, procmail will generate a leading `From
' line if none is present. If one is already present procmail will
leave it intact. If procmail is not invoked with one of the following
user or group ids : root, daemon, uucp, mail, x400, network, list,
slist, lists or news, but still has to generate or accept a new `From '
line, it will generate an additional `>From ' line to help distinguish
fake mails.
For security reasons procmail will only use an absolute or $HOME-
relative rcfile if it is owned by the recipient or root, not world
writable, and the directory it is contained in is not world writable.
The $HOME/.procmailrc file has the additional constraint of not being
group-writable or in a group-writable directory.
If /var/mail/$LOGNAME is a bogus mailbox (i.e., does not belong to the
recipient, is unwritable, is a symbolic link or is a hard link),
procmail will upon startup try to rename it into a file starting with
`BOGUS.$LOGNAME.' and ending in an inode-sequence-code. If this turns
out to be impossible, ORGMAIL will have no initial value, and hence
will inhibit delivery without a proper rcfile.
If /var/mail/$LOGNAME already is a valid mailbox, but has got too loose
permissions on it, procmail will correct this. To prevent procmail
from doing this make sure the u+x bit is set.
When delivering to directories, MH folders, or maildir folders, you
don't need to use lockfiles to prevent several concurrently running
procmail programs from messing up.
Delivering to MH folders is slightly more time consuming than
delivering to normal directories or mailboxes, because procmail has to
search for the next available number (instead of having the filename
immediately available).
On general failure procmail will return EX_CANTCREAT, unless option -t
is specified, in which case it will return EX_TEMPFAIL.
To make `egrepping' of headers more consistent, procmail concatenates
all continued header fields; but only internally. When delivering the
mail, line breaks will appear as before.
If procmail is called under a name not starting with `procmail' (e.g.,
if it is linked to another name and invoked as such), it comes up in
explicit delivery mode, and expects the recipients' names as command
line arguments (as if -d had been specified).
Comsat/biff notifications are done using udp. They are sent off once
when procmail generates the regular logfile entry. The notification
messages have the following extended format (or as close as you can get
when final delivery was not to a file):
$LOGNAME@offset_of_message_in_mailbox:absolute_path_to_mailbox
Whenever procmail itself opens a file to deliver to, it consistently
uses the following kernel locking strategies: fcntl(2).
Procmail is NFS-resistant and eight-bit clean.
NOTES
Calling up procmail with the -h or -? options will cause it to display
a command-line help and recipe flag quick-reference page.
There exists an excellent newbie FAQ about mailfilters (and procmail in
particular); it is maintained by Nancy McGough <nancym@ii.com> and can
be obtained by sending a mail to mail-server@rtfm.mit.edu with the
following in the body:
send usenet/news.answers/mail/filtering-faq
If procmail is not installed globally as the default mail delivery
agent (ask your system administrator), you have to make sure it is
invoked when your mail arrives. In this case your $HOME/.forward
(beware, it has to be world readable) file should contain the line
below. Be sure to include the single and double quotes, and unless you
know your site to be running smrsh (the SendMail Restricted SHell), it
must be an absolute path.
"|exec /usr/bin/procmail"
Some mailers (notably exim) do not currently accept the above syntax.
In such case use this instead:
|/usr/bin/procmail
Procmail can also be invoked to postprocess an already filled system
mailbox. This can be useful if you don't want to or can't use a
$HOME/.forward file (in which case the following script could
periodically be called from within cron(1), or whenever you start
reading mail):
#!/bin/sh
ORGMAIL=/var/mail/$LOGNAME
if cd $HOME &&
test -s $ORGMAIL &&
lockfile -r0 -l1024 .newmail.lock 2>/dev/null
then
trap "rm -f .newmail.lock" 1 2 3 13 15
umask 077
lockfile -l1024 -ml
cat $ORGMAIL >>.newmail &&
cat /dev/null >$ORGMAIL
lockfile -mu
formail -s procmail <.newmail &&
rm -f .newmail
rm -f .newmail.lock
fi
exit 0
A sample small $HOME/.procmailrc:
PATH=/usr/local/bin:/usr/bin:/bin
MAILDIR=$HOME/Mail #you'd better make sure it exists
DEFAULT=$MAILDIR/mbox #completely optional
LOGFILE=$MAILDIR/from #recommended
:0:
* ^From.*berg
from_me
:0
* ^Subject:.*Flame
/dev/null
Other examples for rcfile recipes can be looked up in the procmailex(5)
man page.
SOURCE
This program is part of the procmail mail-processing-package (v3.23pre) available at http://www.procmail.org/ or ftp.procmail.org in pub/procmail/.
MAILINGLIST
There exists a mailinglist for questions relating to any program in the
procmail package:
<procmail-users@procmail.org>
for submitting questions/answers.
<procmail-users-request@procmail.org>
for subscription requests.
If you would like to stay informed about new versions and official
patches send a subscription request to
procmail-announce-request@procmail.org
(this is a readonly list).
AUTHORS
Stephen R. van den Berg
<srb@cuci.nl>
Philip A. Guenther
<guenther@sendmail.com>
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