We use several layers of protection to fight spam and viruses. More Information:
Postscreen - additional protection against mail server overload by keeping spambots away.
Blacklists - Blacklists, Whitelists and Greylists control which connection is legit and which is not.
Postfix Restrictions - postfix specific restriction rules
mtpolicyd - a modular policy daemon for postfix
Virus protection - with ClamAV and Sophos
Spam protection - with SpamAssassin