gr33ndata wrote:
Making the server to sign the mails is a good idea, however it wont wook in public free mails like yahoo, hotmail, gmail, etc as they will not be able to identify spammers from non spammers.

Thats a good point, but I think those guys have ways of handling that. When spam is actually sent through their mailservers they can identify large volumes of mail coming from singular users, or the same mail coming from different users, and flag it for intervention...

RE: A Plan for Ham