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.
Terminate prematurely and requeue the mail.
Terminate prematurely and bounce the mail.
Terminate prematurely and bounce the mail.
QUIT Terminate prematurely and silently lose the mail.
Force a timeout (see TIMEOUT).
USR1 Equivalent to a VERBOSE=off.
Procmail will print its version number, display its compile time configuration and exit.
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.
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).
Instead of allowing anyone to generate `From ' lines, simply override the fakes.
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 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.
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..SH 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.
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.
/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
special privileges path for rcfiles
lockfile for the system mailbox (not automatically used by procmail, unless $DEFAULT equals /var/mail/$LOGNAME and procmail is delivering to $DEFAULT)
default mail forwarder
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
Not a valid environment variable name specified.
Closing brace unexpected
There was no corresponding opening brace (nesting block).
Not all option combinations are useful
Conflicting x suppressed
Flag x is not compatible with some other flag on this recipe.
The system mailbox was missing and could not/will not be created.
Couldn't create maildir part
The maildir folder
Couldn't create or rename temp file
An error occurred in the mechanics of delivering to the directory folder
Couldn't determine implicit lockfile from
There were no `
Procmail was unable to open an rc- file or it was not a regular file, or procmail couldn't open an MH di- rectory to find the highest num- bered file.
Lockfile was already gone, or write permission to the directory where the lockfile is has been denied.
Deadlock attempted on
The locallockfile specified on this recipe is equal to a still active $LOCKFILE.
Denying special privileges for
Procmail will not take on the iden- tity that comes with the rcfile be- cause a security violation was found (e.g. -p or variable assign- ments on the command line) or proc- mail had insufficient privileges to do so.
As procmail was started, stdin, stdout or stderr was not connected (possibly an attempt to subvert se- curity)
Enforcing stricter permissions on
The system mailbox of the recipient was found to be unsecured, procmail secured it.
Error while writing to
Nonexistent subdirectory, no write permission, pipe died or disk full.
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
The program or filter
Extraneous x ignored
The action line or other flags on this recipe makes flag x meaning- less.
Process table is full (and NORES- RETRY has been exhausted).
Failed to execute
Program not in path, or not exe- cutable.
Forced unlock denied on
No write permission in the directo- ry where lockfile __
Forcing lock on
The start of a recipe was found, but it stranded in an EOF.
Procmail either needs root privi- leges, or must have the right (e)uid and (e)gid to run in deliv- ery mode. The mail will bounce.
The regular expression
While trying to use the kernel-sup- ported locking calls, one of them failed (usually indicates an OS er- ror), procmail ignores this error and proceeds.
Lock failure on
Can only occur if you specify some real weird (and illegal) lockfile- names or if the lockfile could not be created because of insufficient permissions or nonexistent subdi- rectories.
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.
You specified the -a option but forgot the argument.
Missing rcfile You speci- fied the -m option, procmail ex- pects the name of an rcfile as ar- gument.
You specified the -d option or called procmail under a different name, it expects one or more recip- ients as arguments.
No space left to finish writing
The filesystem containing
Out of memory The system is out of swap space (and NORES- RETRY has been exhausted).
The unrecognised options on the command line are ignored, proceed- ing as usual.
Program failure (nnn) of
Program that was started by proc- mail returned nnn instead of EX- IT_SUCCESS (=0); if nnn is nega- tive, then this is the signal the program died on.
Quota exceeded while writing
The filesize quota for the recipi- ent on the filesystem containing
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.
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 ei- ther 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 has occurred on program or filter
Timeout, was waiting for
Timeout has occurred on program, filter or file
Truncated file to former size
The file could not be delivered to successfully, so the file was trun- cated to its former size.
Unable to treat as directory
Either the suffix on
Unexpected EOL Missing closing quote, or trying to escape EOF.
Extended diagnostics can be turned on and off through set- ting the VERBOSE variable.
Procmail's pid and a timestamp. Generated whenever procmail logs a diagnostic and at least a second has elapsed since the last times- tamp.
Procmail now tries to kernel-lock the most recently opened file (de- scriptor).
Assuming identity of the recipient, VERBOSE=off
Dropping all privileges (if any), implicitly turns off extended diag- nostics.
The mail spool directory was not accessible to procmail, it relied solely on kernel locks.
This host was called
No match on
Non-zero exitcode (nnn) by
Program that was started by proc- mail as a condition or as the ac- tion of a recipe with the `W' flag returned nnn instead of EXIT_SUC- CESS (=0); the usage indicates that this is not an entirely unexpected condition.
Sent comsat/biff a notice that mail arrived for user $LOGNAME at `off- set' in `file'.
While attempting several locking methods, one of these failed. Procmail will reiterate until they all succeed in rapid succession.
Score: added newtotal
This condition scored `added' points, which resulted in a `newto- tal' score.
You should create a shell script that uses lockfile(1) be- fore 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 subsec- tion 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 rc- file), the system mailqueue could fill up. This could ag- gravate both the local postmaster and other users.
The /etc/procmailrc file might be executed with root priv- ileges, 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 securi- ty, make sure this directory is executable to root only.
After removing a lockfile by force, procmail waits $SUS- PEND seconds before creating a new lockfile so that anoth- er 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 correct- ly.
If there is an existing Content-Length: field in the head- er of the mail and the -Y option is not specified, proc- mail 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 mailfold- ers, any lines in the body of the message that look like postmarks are prepended with ` __
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 de- livery 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 de- fault 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 al- ready 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 `
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 con- tained 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 re- name it into a file starting with `BOGUS.$LOGNAME.' and ending in an inode-sequence-code. If this turns out to be impossible, ORGMAIL will have no initial value, and hence will inhibit delivery without a proper rcfile.
If /var/mail/$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 sever- al concurrently running procmail programs from messing up.
Delivering to MH folders is slightly more time consuming than delivering to normal directories or mailboxes, be- cause procmail has to search for the next available number (instead of having the filename immediately available).
On general failure procmail will return EX_CANTCREAT, un- less 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 inter- nally. 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 in- voked as such), it comes up in explicit delivery mode, and expects the recipients' names as command line arguments (as if -d had been specified).
Whenever procmail itself opens a file to deliver to, it consistently uses the following kernel locking strategies: fcntl(2).
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?
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 $HOME/.forward (beware, it has to be world readable) file should contain the line below. Be sure to include the single and double quotes, and unless you know your site to be running smrsh (the !SendMail Restricted SHell), it must be an absolute path.
Some mailers (notably exim) do not currently accept the above syntax. In such case use this instead:
ORGMAIL=/var/mail/$LOGNAME if cd $HOME
A sample small $HOME/.procmailrc:
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