BitDefender Antispam for Mail Servers (Win SMTP Proxy) uses six proprietary modules to keep unwanted e-mail out of your organization: IP Match, Keyword Filter, White List/Blacklist, Charset Filter, URL Filter, Heuristic Filter. BitDefender AntiSpam checks every incoming & outgoing email message and attaches a Spam Score. If the spam score is greater than or equal to the spam threshold, then the message is marked as spam. Otherwise, it's marked as ham (non-spam). For complete protection, BitDefender Antispam for Mail Servers (WIN SMTP Proxy) can also be installed along with BitDefender for MS Exchange 5.5 and BitDefender for Lotus Domino. BitDefender Antispam for Mail Servers (WIN SMTP Proxy) should not be installed along with BitDefender for MS Exchange 2003, BitDefender for MS Exchange 2000 or BitDefender Antivirus & Antispam for Mail Servers (WIN SMTP Proxy), because all these products already provide both antivirus and antispam protection.