Mail User Agents - Red Hat ENTERPRISE LINUX 3 Reference Manual

176 Chapter 11. Email
11.4.2.6. 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 to-
gether, 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
file:
~/.procmailrc
INCLUDERC=/etc/mail/spamassassin/spamassassin-default.rc
The contains a simple Procmail rule
/etc/mail/spamassassin/spamassassin-default.rc
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.
To file email tagged as spam, a rule similar to the following can be used:
:0 Hw
* ^X-Spam-Status: Yes
spam
This rule files all email tagged in the header as spam into a mailbox called .
spam
Since SpamAssassin is a Perl script, it may be necessary on busy servers to use the binary SpamAssas-
sin daemon ( ) and client application ( ). Configuring SpamAssassin this way, however,
spamd spamc
requires root access to the host.
To start the daemon, type the following command as root:
spamd
/sbin/service spamassassin start
To start the SpamAssassin daemon when the system is booted, use an initscript utility, such as the
Services Configuration Tool ( ), to turn on the service.
redhat-config-services spamassassin
Refer to Section 1.4.2 Runlevel Utilities for more information about initscript utilities.
To configure Procmail to use the SpamAssassin client application instead of the Perl script, place the
following line near the top of the file. For a system-wide configuration, place it in
~/.procmailrc
:
/etc/procmailrc
INCLUDERC=/etc/mail/spamassassin/spamassassin-spamc.rc

11.5. Mail User Agents

There are scores of mail programs available under Red Hat Enterprise Linux. There are full-featured,
graphical email client programs, such as Mozilla Mail or Ximian Evolution, as well as text-based
email programs such as .
mutt
For instructions on using these applications, refer to the chapter titled Email Applications in the Red
Hat Enterprise Linux Step By Step Guide.