Sendmail

Blacklisting

It is not uncommon to look in your mail logs (these are kept in /var/log/maillog) or your firewall logs and notice some rogue IPs attempting to relay through your server or spam you directly. If these IPs are consistent you can always add them to your access table (and recompile of course).

The Access file is also used to list the IPs that you want to permit relaying through. Typically this would be the IPs of your office and/or home.

#/etc/mail/access
#run makemap hash /etc/mail/access < /etc/mail/access
# by default we allow relaying from localhost...
localhost.localdomain RELAY
localhost                     RELAY
127.0.0.1                    RELAY
66.55.44.245              RELAY

#Allow a friend's ISP to relay
22.22.33                     RELAY
customer.com             RELAY

#Blocking
wanadoo.fr     550 We don't accept mail from spammers
gov.ru             550 We don't accept mail from spammers
mail.ru            550 We don't accept mail from spammers

After you have edited your access file you must run this command from the prompt:

makemap hash /etc/mail/access < /etc/mail/access

CLUE: Using the access file to blacklist someone only prevents them from accessing sendmail, If you want TOTAL blocking from any and all TCP/IP ports you should use the /etc/hosts.deny file or an entry in IPTables.

Continue to Spam Filtering for Sendmail ->

Article last reviewed: 10/09/2006

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