Sendmail : Spam Filtering

After configure the following steps, Sendmail won’t even talk to spam anymore.

Editing the file /etc/mail/sendmail.mc, insert the following lines anywhere in the FEATURE section of the file:

dnl #
dnl # Here are Sharky's favorite DNSBL definitions.
dnl #
FEATURE(`dnsbl', `list.dsbl.org')dnl
FEATURE(`dnsbl', `bl.spamcop.net')dnl
FEATURE(`dnsbl', `sbl.spamhaus.org')dnl
FEATURE(`dnsbl', `blackholes.mail-abuse.org')dnl
FEATURE(`dnsbl', `relays.mail-abuse.org')dnl

Apply the changes by saving the file and running the following commands:

service sendmail restart

From this point on, every time an SMTP client connects to Sendmail, Sendmail will refer to the blacklist authorities you added to verify the client’s reputation. If the client is reported to have a shady reputation, Sendmail will hang up on him.