Separating Wheat from the Chaff: A Deployable Approach to Counter Spam

Unsolicited bulk email, aka spam is a persistent threat to the usefulness of the Internet. The fight against spam today relies solely on filtering at the recipientÕs mail server, which can delay mail delivery. We present a spam countering approach consisting of two complementary techniques. The first, token-based authentication, can identify emails from valid senders that a user expects to hear from. This identification prevents much of the good mail from being subjected to the filtering process. The second technique, history-based prioritization, is designed for the rest of the email. It utilizes past information about the sending mail servers and their domains to prioritize email filtration, thus reducing delays in the delivery of good email over spam. The proposed techniques do not rely on any infrastructure, deployed or otherwise, and any mail server can choose to deploy them independent of the choice made by the any other mail server.