Bringing Identity to Email

End of the road for SMTP? | CNET News.com

The hard part, according to Hoffman and others, is establishing the "trust relationships" required to back up any computer-based authentication scheme--in other words, verifying that a person is who he or she claims to be.

The problem worsens, Hoffman said, when trying to design a system that authenticates mail servers, rather than individuals. In part, this is because a third party would have to determine whether an e-mail server is responsible for sending spam. That kind of responsibility--voluntarily assumed by operators of various spam blacklists--could be onerous and expensive, if applied to the Internet as a whole.

"Who is paying this third party for both the time and the legal risk in doing this?" Hoffman asked.