Sendmail

Spam and Virus Filtering

Step 1: Back up important files

cd /etc/mail cp sendmail.mc sendmail.mc.old cp sendmail.cf sendmail.cf.old

Step 2: Install needed packages:

cd /etc/yum.repos.d
wget http://centos.karan.org/kbsingh-CentOS-Extras.repo
wget http://centos.karan.org/kbsingh-CentOS-Misc.repo
yum install clamav* spamass-milter pyzor perl-Razor-agent

Step 3: Edit /etc/mail/sendmail.mc

Paste these lines of code toward the end of the file before the line that says: MAILER(smtp)dnl

#DNS Black Lists

dnl FEATURE(`dnsbl', `ipwhois.rfc-ignorant.org',`"550 Mail from " $&{client_addr} " refused. Rejected for bad WHOIS info on IP of your SMTP server - see http://www.rfc-ignorant.org/"')

dnl FEATURE(`dnsbl', `proxies.blackholes.easynet.nl', `"550 5.7.1 ACCESS DENIED to OPEN PROXY SERVER "$&{client_name}" by easynet.nl DNSBL (http://proxies.blackholes.easynet.nl/errors.html)"', `')

dnl FEATURE(`dnsbl',`sbl.spamhaus.org',`Rejected - see http://spamhaus.org/')

dnl FEATURE(`dnsbl', `bl.spamcop.net', `"450 Mail from " $`'&{client_addr} " refused - see http://spamcop.net/bl.shtml"')

#Spamassassin and Clam Anti-virus Filter (milter)

INPUT_MAIL_FILTER(`spamassassin', `S=local:/var/run/spamass-milter/spamass-milter.sock, F=,T=C:15m;S:4m;R:4m;E:10m')dnl

INPUT_MAIL_FILTER(`clamav', `S=local:/var/run/clamav-milter/clamav.sock, F=T, T=S:4m;R:4m')

Note: These lines are really long, so I added an extra line break in between to improve clarity.

Step 4: Rebuild the Sendmail Config file

m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf

Step 5: Turn on Virus Filtering

Open /etc/freshclam.conf and look for the Line that starts with the word: EXAMPLE Please just comment it out by prepending a # to make the line read: #EXAMPLE

Open /etc/clam.d/milter.conf and look for the Line that starts with the word: EXAMPLE Please just comment it out by prepending a # to make the line read: #EXAMPLE

Spam Configuration - Part 2 ->

References:

Sample Sendmail configuration file

Spam proof and Virus Filtering e-mail server -
http://www.centos.org/modules/newbb/viewtopic.php?topic_id=4938

Centralized Spam Filtering:
http://www.stearns.org/doc/spamassassin-setup.current.html#sitewide

Spam Assassin Configurator:
http://www.yrex.com/spam/spamconfig.php

Article last reviewed: 12/29/2006

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