Spam filtering – Spamassassin and Procmail on Redhat Linux
Spamassassin filters out allmost all spam without user made rules.
This document (or mini-howto) explains how to install spamassin system
wide in redhat.
This document is also
available in in Hindi (pdf), translated by Kalpana Chatnani.
Install spamassassin
If you are using yum,
install with
yum -y install spamassassin procmail
Spamassassin is invoked by procmail when new mail arrives. Add
spamasssain to all users by editing nano /etc/procmailrc
# /etc/procmailrc for redhat (c) 2003 Tero.Karvinen atsign iki.fi
DROPPRIVS=1
:0fw:spamassassin.lock
* < 256000
|/usr/bin/spamassassin
:0
* ^X-Spam-Status: Yes
$HOME/mail/spam
If you don’t want to force you users to filtering spam, you can
just tag spam in /etc/procmailrc by commenting out
the $HOME/mail/spam rule (last 3 lines). Users
can then use $HOME/.procmailrc to handle spam
as they see fit.
If your system has a lot of users, consider using spamd.
Rules improved
Spamassassin works great out of the box, no user configuration needed.
Especially, there is no reason to create large blacklists of hosts you
don’t want to receive mail from.
Improved rules:
# /etc/mail/spamassassin/local.cf (c) 2003 Tero Karvinen
# Local.cf must be world readable (chmod a+r local.cf)
# Users can override settings with $HOME/.spamassassin/user_prefs
# required_hits 5
# whitelist_from *@somewhere.com
# Image link to track mail viewing - score WEB_BUGS -0.430
# Default rule is too narrow: /]*src[^>]+?/i
score WEB_BUGS 2.5
# HTML-only mail, with no text version - score CTYPE_JUST_HTML 1.665
score CTYPE_JUST_HTML 3
# HTML attachment - score __CTYPE_IS_HTML 0
score __CTYPE_IS_HTML 0.6
# Message includes Microsoft executable program - score MICROSOFT_EXECUTABLE 0.100
MICROSOFT_EXECUTABLE 2
# Osirusoft is closed and blocks the world
score RCVD_IN_OSIRUSOFT_COM 0.0
score X_OSIRU_DUL 0.0
score X_OSIRU_DUL_FH 0.0
score X_OSIRU_OPEN_RELAY 0.0
score X_OSIRU_SPAMWARE_SITE 0.0
score X_OSIRU_SPAM_SRC 0.0
Links
See Mika
Hirvonen’s website for improved Spamassassin rpms and baynesian filtering.
Adminstrivia
Todo: Write guide to some baynesian filter, they get better results
nowadays.
This howto was tested with redhat 9.0.
Copyright 2003-mm-dd, 2003-09-28 Tero Karvinen. GNU Free Documentation
Licence.
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