procmail - autonomous mail processor
] [-f fromwhom
] [-f fromwhom
] ... -d recipient
] [-a argument
For a quick start, see NOTES
at the end.
should be invoked automatically over the .forward
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
. 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
(if present). Care must be taken when
creating /usr/local/etc/procmailrc, because, if circumstances permit, it will
be executed with root privileges (contrary to the $HOME/.procmailrc file of
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
(5) man page.
Examples for rcfile recipes can be looked up in the procmailex
- Terminate prematurely and requeue the mail.
- Terminate prematurely and bounce the mail.
- Terminate prematurely and bounce the mail.
- Terminate prematurely and silently lose the mail.
- Force a timeout (see TIMEOUT).
- Equivalent to a VERBOSE=off.
- Equivalent to a VERBOSE=on.
- 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.
- -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).
- Instead of allowing anyone to generate `From ' lines, simply override the
- Assume traditional Berkeley mailbox format, ignore any
- -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
- -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 /usr/local/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.
- 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 variables and the ones specified on the command line.
Examples for rcfile recipes can be looked up in the procmailex
page. A small sample rcfile can be found in the NOTES
Skip the rest of this EXAMPLES section unless you are a system administrator who
is vaguely familiar with sendmail.cf syntax.
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/local/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 $:$email@example.com$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 loop.
- 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
- initial global rcfile
- special privileges path for rcfiles
- default rcfile
- lockfile for the system mailbox (not automatically used by procmail,
unless $DEFAULT equals /var/mail/$LOGNAME and procmail is delivering to
- default mail forwarder
- temporary `unique' zero-length files created by procmail
- 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
- 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 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- Skipped: "x"
- Couldn't do anything with "x" in the rcfile (syntax error),
- 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
- 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
- [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
- Assigning "x"
- Environment variable assignment.
- Assuming identity of the recipient, VERBOSE=off
- Dropping all privileges (if any), implicitly turns off extended
- 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'
- 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'
- 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
-9, see the subsection Signals
for suggestions), otherwise some
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.
file might be executed with root
privileges, so be very careful of what you put in it. SHELL
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 :
Keep in mind that if chown
(1) is permitted on files in
, 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
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.
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
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
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, news, mailnull,
majordom or majordomo, but still has to generate or accept a new `From ' line,
it will generate an additional `>From ' line to help distinguish fake
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 $HOME/.procmailrc file has the
additional constraint of not being group-writable or in a group-writable
If /var/mail/$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.$LOGNAME.' and
ending in an inode-sequence-code. If this turns out to be impossible,
will have no
initial value, and hence will inhibit
delivery without a proper rcfile.
If /var/mail/$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
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):
Whenever procmail itself opens a file to deliver to, it consistently uses the
following kernel locking strategies : lockf
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 <firstname.lastname@example.org> and can
be obtained by sending a mail to email@example.com 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 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
" |exec /usr/local/bin/procmail | | exit 75"
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
(1), or whenever you start reading mail):
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
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
This program is part of the procmail mail-processing-package
available at http://www.procmail.org/ or ftp.procmail.org in
There exists a mailinglist for questions relating to any program in the procmail
for submitting questions/answers.
for subscription requests.
If you would like to stay informed about new versions and official patches send
a subscription request to
(this is a readonly list).
Stephen R. van den Berg
Philip A. Guenther