Microsoft Supports SenderID in Exchange

Microsoft's apparently ill-fated anti-spam software technology, SenderID, will be included in an upcoming service pack to Exchange Server 2003.

SenderID helps participating servers authenticate the identity of the sending party of an email. By itself it doesn't do anything to halt spam. However, it could hypothetically be used in conjunction with lists of known good and bad senders to provide filtering.

It could most effectively be used as a data point within a fuzzy logic or Bayesian filtering system. Known good senders would get an automatic pass. Known bad senders could be subject to strict evaluation by spam stoppers. Senders which aren't verifiable could be subject to a mid-level filtering algorithm.

What's not clear is how much benefit this provides email spam filters over a traditional DNS based blacklist. There are currently dozens, if not over a hundred different independently run databases of known spammers. SenderID would seem to provide an additional mechanism besides just IP address to verify identity. It's not apparent how much added benefit this would provide.

Over the last year, Microsoft's partners in promoting SenderID have ditched the technology one by one. Microsoft has specifically had trouble wooing the open source community in supporting. This is at least partly due to it wanting to maintain certain patents on the technology.

A large portion of email servers run on open source software. Any new anti-spam email technology would likely need the support open source contributors in order to succeed.

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