Christian Huitema writes: > > However, creating new publick/private key pairs is an incredibly > > expensive operation, and one that a legitimate email wouldn't have to > > do very often, but a spammer would if we just keep blacklisting their > > keys. > > Uh? Creating a Diffie-Hellman public/private key pair is actually quite > simple. Even an RSA pair is not all that hard, considering that a set of > N prime numbers can generate N.(N-1)/2 key pairs. The logical > consequence of authenticated e-mail is bound to be authenticated spam... You don't see that as a step in the right direction? Mike