Procmail is a program that can process e-mails according to a set of rules defined in a configuration file. Rules consist of condition/action pairs. The condition can be any test related to the email header or content. The action can be forwarding the e-mail to a program or placing it into a mailbox. This howto uses a simple example to explain how to dispatch e-mails to different mailboxes according to pre-defined filters.

In typical uses, procmail is instantiated by the local MTA through the .forward script. The .forward scrip placed in the user's home directory would contain the following lines:

 | /usr/bin/procmail

With this setting, all e-mails will be forwarded to the procmail program. From there, procmail will be responsible for delivering them to a local mailbox, forwarding to an e-mail address or delivering them to another program.

To tell procmail what to do with e-mails that it receives from the local MTA, we need to create a configuration file.

Typically, each account using the .forward script will also need to create a .procmailrc configuration file. Below is an example from a configuration file that I am using. Amongst other things it causes procmail to deliver e-mails from mailing lists to appropriate mailboxes.

# Change these according to your environment
MAILDIR=$HOME/Mail
DEFAULT=$MAILDIR/mbox
LOGFILE=$HOME/from
LOCKFILE=$HOME/.lockmail
BACKUP=other@email.com
 
 
# Save e-mails from somewhere.com mailing list to the SOMEWHERE mailbox
:0:
* ^From.*@somewhere\.com
SOMEWHERE
 
# Save e-mails from IETF mailing lists to the IETF mailbox
:0:
* List-Id:.*ietf
IETF
 
 
# Save Important e-mails to the IMPORTANT mailbox, then forward a copy to the back-up e-mail.
:0:
* ^Subject.*Important*
{
        :0 c
        IMPORTANT
 
        :0
        ! $BACKUP
}
 
 
# Place the e-mail into a folder by date (e.g. Dec-2009).
:0:
*
`date +%b-%Y`

Labels: howto, unix