ProcMail stands for Mail Processing, it allows you to process your incoming mail and then sort it into separate folders/file. ProcMail can be used to setup a vacation message or to forward your mail to another email address. All in all, it can be used for many things and I don’t even know them all :) I will break this guide into two parts: install and setup.

Install ProcMail

Download the source from the following URL. You should get a file that looks similar to this procmail-3.22.tar.gz. Now let’s begin installing.

mv procmail-3.22.tar.gz /tmp; cd /tmp  
tar xzf procmail-3.22.tar.gz; cd procmail-3.22  
make  
make BASENAME=/usr/local/procmail install

After Install Instructions

sudo chown 0:0 -R /usr/local/procmail  
sudo chmod 6755 /usr/local/procmail/bin/procmail  
sudo chmod 2755 /usr/local/procmail/bin/lockfile

Setup Instructions

Any time mail comes to the server, whether the mail server is running sendmail or exim or any other mail server software, by default most of the mail services look at the ~/.forward file. If the file exists then mail is either forwarded to the email address that is in the .forward file, or the mail server executes whatever is in that file. To use procmail we need to add an entry in .forward so it is executed whenever any email comes in. So if we place the following into our ~/.forward file we should be all set.

"|IFS=' '&&exec /usr/local/procmail/bin/procmail -f-||exit 75 #username"

note: replace username with your username

Example to use SpamAssassin with ProcMail

Spamassassin is a linux utility which finds spam in mail and adds a header to the email message to mark as spam. Spamassassin is a perl-based application. Using your favorite text editor put the following into your ~/.procmailrc

# .procmailrc  
#  
DEFAULT=/var/mail/$LOGNAME  
UMASK=007

# Look for spam  
:0fw  
| /usr/local/perl/bin/spamassassin  
:0  
*^X-Spam-Flag:Yes  
*^Subject: POTENTIAL SPAM:  
$HOME/mail/spam

:0:  
$DEFAULT

Here is what happens, each message is run through the spamassassin utility which checks if it is spam. If it’s spam it will mark it so by adding the X-Spam-Flag:Yes header field and prepend POTENTIAL SPAM: to the subject line. So after we run the message through spamassassin and if the above has been set, we can then move the message to the spam folder … see that was simple, wasn’t it ?

Example to forward messages to your gmail account

Place the following into your ~/.procmailrc:

#  
# .procmailrc  
#  
DEFAULT=/var/mail/$LOGNAME  
UMASK=007

# Forward all mail to gmail  
:0c  
! your_gmail_address@gmail.com

:0:  
$DEFAULT