I think that any loading of e-mail with computational tasks has to follow the paradigm of the current system, where A sends mail to B and there is absolutely no other communication betwen B and A or C for that matter. For instance, take an assymetric algo, where t=Hard(x) and x=Easy(t). x is something that B can verify is (almost) unique to the message, like x = (B's e-mail address) + timestamp (must be within last n hours). A burns cycles to do t=Hard(x) and sends t with the message to B. B verifies x with x=Easy(t) and accepts or rejects message based on that. The drawback is that sending any mail costs time. I queue mail and in few minutes t is computed and mail sent. It could be as little as minute per message to discourage spam. No intermediaries, no communication protocols. ===== end (of original message) Y-a*h*o-o (yes, they scan for this) spam follows: __________________________________ Do you Yahoo!? The New Yahoo! Search - Faster. Easier. Bingo. http://search.yahoo.com