procmail - autonomous mail processor
procmail [-ptoY] [-f fromwhom]
[parameter=value | rcfile] ...
procmail [-toY] [-f fromwhom] [-a argument] ...
-d recipient ...
procmail [-ptY] -m [parameter=value] ... rcfile
procmail [-toY] [-a argument] -z
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 (and in the standard Red
Hat Linux configuration), it can be invoked from within the mailer immediately. When
invoked, it first sets some environment variables to default values, reads the mail mes-
sage 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. Accord-
ing to the processing recipes in this file, the mail message that just arrived gets dis-
tributed 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 func-
tionally 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.
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.
-v Procmail will print its version number, display its compile time configuration and
-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 environ-
ment 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.
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.
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 send-
mail 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/procmail-
rcs/ 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.
-z This turns on LMTP mode, wherein procmail acts as an RFC2033 LMTP server. Delivery
takes place in the same manner and under the same restrictions as the delivery mode
enabled with -d. This option is incompatible with -p and -f.
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 vari-
ables and the ones specified on the command line.
Examples for rcfile recipes can be looked up in the procmailex(5) man page. A small sam-
ple 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 send-
mail.cf file. In order to be able to do this it is convenient to create an extra `proc-
mail' 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
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):
$#procmail $@/etc/procmailrcs/some.rc $:$firstname.lastname@example.org$2
$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 $@
:0 # sink all junk mail
:0 w # pass along all other mail
! -oi -f "$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
/etc/passwd to set the recipient's LOGNAME, HOME and SHELL variable defaults
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
lockfile for the system mailbox (not automatically used by proc-
mail, unless $DEFAULT equals /var/spool/mail/$LOGNAME and procmail
is delivering to $DEFAULT)
/usr/sbin/sendmail default mail forwarder
_????`hostname` temporary `unique' zero-length files created by procmail
procmailrc(5), procmailsc(5), procmailex(5), sh(1), csh(1), mail(1), mailx(1), binmail(1),
uucp(1), aliases(5), sendmail(8), egrep(1), grep(1), biff(1), comsat(8), lockfile(1),
Autoforwarding mailbox found
The system mailbox had its suid or sgid bit set, procmail termi-
nates with EX_NOUSER assuming that this mailbox must not be deliv-
Bad substitution of "x"
Not a valid environment variable name specified.
Closing brace unexpected
There was no corresponding opening brace (nesting block).
Conflicting options Not all option combinations are useful
Conflicting x suppressed
Flag x is not compatible with some other flag on this recipe.
Couldn't create "x" The system mailbox was missing and could not/will not be created.
Couldn't create maildir part "x"
The maildir folder "x" is missing one or more required subdirecto-
ries and procmail could not create them.
Couldn't create or rename temp file "x"
An error occurred in the mechanics of delivering to the directory
Couldn't determine implicit lockfile from "x"
There were no `>>' redirectors to be found, using simply `$LOCKEXT'
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 num-
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 ac-
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 as-
signments on the command line) or procmail had insufficient privi-
leges 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
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
Extraneous x ignored The action line or other flags on this recipe makes flag x meaning-
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
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.
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 miss-
ing 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
Kernel-unlock failed See above.
Lock failure on "x" Can only occur if you specify some real weird (and illegal) lock-
filenames or if the lockfile could not be created because of insuf-
ficient 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
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 exhaust-
Processing continued The unrecognised options on the command line are ignored, proceed-
ing as usual.
Program failure (nnn) of "x"
Program that was started by procmail returned nnn instead of EX-
IT_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
Skipped: "x" Couldn't do anything with "x" in the rcfile (syntax error), ignor-
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 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 time-
Acquiring kernel-lock Procmail now tries to kernel-lock the most recently opened file
Assigning "x" Environment variable assignment.
Assuming identity of the recipient, VERBOSE=off
Dropping all privileges (if any), implicitly turns off extended di-
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 (with-
out 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 ac-
tion of a recipe with the `W' flag returned nnn instead of EX-
IT_SUCCESS (=0); the usage indicates that this is not an entirely
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".
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 `newto-
Unlocking "x" Removing lockfile "x" again.
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 aggra-
vate 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 : DROP-
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 config-
ure your MTA to add some headers with the envelope recipient data in order to tell Proc-
mail 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.
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 be-
ing treated as a single space as they are now.
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 ap-
pends to regular mailfolders, any lines in the body of the message that look like post-
marks are prepended with `>' (disarms bogus mailheaders). The regular expression that is
used to search for these postmarks is:
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 en-
try, 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 in-
voked with one of the following user or group ids: root, daemon, uucp, mail, x400, net-
work, 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 $HOME/.procmailrc file has the additional constraint of not
being group-writable or in a group-writable directory.
If /var/spool/mail/$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 re-
name it into a file starting with `BOGUS.$LOGNAME.' and ending in an inode-sequence-code.
If this turns out to be impossible, ORGMAIL will have no initial value, and hence will in-
hibit delivery without a proper rcfile.
If /var/spool/mail/$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 direc-
tories 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 gener-
ates 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):
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.
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 <email@example.com> and can be obtained by sending a mail to mail-
firstname.lastname@example.org with the following in the body:
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 be-
low. 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.
Some mailers (notably exim) do not currently accept the above syntax. In such case use
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 follow-
ing script could periodically be called from within cron(1), or whenever you start reading
if cd $HOME &&
test -s $ORGMAIL &&
lockfile -r0 -l1024 .newmail.lock 2>/dev/null
trap "rm -f .newmail.lock" 1 2 3 13 15
lockfile -l1024 -ml
cat $ORGMAIL >>.newmail &&
cat /dev/null >$ORGMAIL
formail -s procmail <.newmail &&
rm -f .newmail
rm -f .newmail.lock
A sample small $HOME/.procmailrc:
MAILDIR=$HOME/Mail #you'd better make sure it exists
DEFAULT=$MAILDIR/mbox #completely optional
Other examples for rcfile recipes can be looked up in the procmailex(5) man page.
This program is part of the procmail mail-processing-package (v3.22) available at
http://www.procmail.org/ or ftp.procmail.org in pub/procmail/.
There exists a mailinglist for questions relating to any program in the procmail package:
for submitting questions/answers.
for subscription requests.
If you would like to stay informed about new versions and official patches send a sub-
scription request to
(this is a readonly list).
Stephen R. van den Berg
Philip A. Guenther
BuGless 2001/08/27 PROCMAIL(1)