Fine Grain Spam Suppression Using Reachback

A system is proposed that is capable of identifying the true originator of an email message. This information can be combined with existing whitelist and blacklist technology to provide an effective anti-spam system. The approach is to store validation information that can be traced to the sender and to utilize a “Reachback URL” in the message to access the validation information. The approach proposed here has a number of advantages over existing systems. It does not require use of DNS, it can use the existing email distribution system, it is robust against in-transit header modifications and mail forwarding, and it can identify sources down to the granularity of individual email addresses. It can be incrementally deployed by individual users and can provide incremental value through automated