Red Hat ENTERPRISE LINUX 5 - DEPLOYMENT Deployment Manual page 423

With this example, any messages sent by spammer@domain.com are sent to the /dev/null device,
deleting them.
Caution
Be certain that rules are working as intended before sending messages to /dev/null
for permanent deletion. If a recipe inadvertently catches unintended messages, and those
messages disappear, it becomes difficult to troubleshoot the rule.
A better solution is to point the recipe's action to a special mailbox, which can be
checked from time to time to look for false positives. Once satisfied that no messages
are accidentally being matched, delete the mailbox and direct the action to send the
messages to /dev/null.
The following recipe grabs email sent from a particular mailing list and places it in a specified folder.
:0:
* ^(From|CC|To).*tux-lug
tuxlug
Any messages sent from the tux-lug@domain.com mailing list are placed in the tuxlug mailbox
automatically for the MUA. Note that the condition in this example matches the message if it has the
mailing list's email address on the From, CC, or To lines.
Consult the many Procmail online resources available in
detailed and powerful recipes.
24.5.2.6. Spam Filters
Because it is called by Sendmail, Postfix, and Fetchmail upon receiving new emails, Procmail can be
used as a powerful tool for combating spam.
This is particularly true when Procmail is used in conjunction with SpamAssassin. When used
together, these two applications can quickly identify spam emails, and sort or destroy them.
SpamAssassin uses header analysis, text analysis, blacklists, a spam-tracking database, and self-
learning Bayesian spam analysis to quickly and accurately identify and tag spam.
The easiest way for a local user to use SpamAssassin is to place the following line near the top of the
~/.procmailrc file:
INCLUDERC=/etc/mail/spamassassin/spamassassin-default.rc
The /etc/mail/spamassassin/spamassassin-default.rc contains a simple Procmail rule
that activates SpamAssassin for all incoming email. If an email is determined to be spam, it is tagged
in the header as such and the title is prepended with the following pattern:
*****SPAM*****
The message body of the email is also prepended with a running tally of what elements caused it to be
diagnosed as spam.
Section 24.7, "Additional Resources"
Procmail Recipes
for more
397