The SFDC (SpamFilter Distributed Content) filter is a propietary filtering technology developed by LogSat Software.
When SpamFilter ISP receives an email, it will analyze the email's contents and will calculate a 20-byte hash to characterize it. We developed technology that is able to detect similar emails based on their contents. SpamFilter will assign the same hash to similar emails. When SpamFilter detects that emails with the same hash signature are originating from several different locations, it will report such anomaly to our centralized servers.
Our database analyzes, in real-time, this incoming flow of messages, and, based on their quantity, origin and destinations, is able to detect what signature hashes are generated by spam emails.
The technology behind the SFDC allows our centralized database to detect spam signatures regardless of the email's text and contents, but rather base it on the patterns used by spammers to deliver their emails.