Provided by: procmail_3.22-16ubuntu5_i386 bug

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
       dont 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  (v3.22)
       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>