DomainKeys

DomainKeys is Yahoo!’s answer to fighting SPAM. Along the same lines as SPF; using Public Key Cryptography we can verify the authenticity of the message’s sender and that the message has not been alterted in transit; thus allowing us to build up a list of “good domains” and “bad domains”. So far it looks like Google’s Gmail is the only big name to implement DomainKeys yet; see the Slashdot article for more information.