SMTP Trap is a spam killer software. This spam blocker is feature rich. It acts as a proxy between your mail server and the Internet. It intercepts every incoming message and analyzes it based upon the rules setup by you. The spam blocker is a server-based junk mail filter and works in conjunction with a mail server. Based upon the rules, the spam killer deletes junk emails rather than passing them to the mail server. This happens way before the messages are delivered to your inbox of your favorite email programs like Outlook and Eudora.
SMTP Trap blocks spam by MX lookup failure, blocks spam by Reverse lookup failure, allows certain IPs/domains based upon a list, supports authenticated SMTP (RFC 2554) for your mail server's valid users, blocks certain IPs/domains based upon a list, supports muli-home mail server, blocks spam based upon sender, receiver, and upon regular expression search in subject or body. It runs as windows service.