Spammers embrace email authentication The Register: "long as spammers comply with the protocol by not spoofing the sender address, their messages will not be stopped by SPF, which "
The only way the spam problem will get solved is when there is a cost associated with sending email. It's a classic "tragedy of the commons" problem from economic theory. Great Britain experience the same problem with their postal system 200 years ago when advertisers got the idea of using the printing press to do mass mailings--back in those days, the receiver of the mail paid for the postage. It became a big problem and almost killed the postal system until they invented stamps. The invention of stamps allowed senders to be charged for the mail. We need the electronic version of stamps to solve the spam problem. The great part is that normal people would probably never see the cost of the postage, as they send less than they receive--thus the cost of postage could be offset by the revenue from postage for normal people, while the spammer/advertisers end up paying for the system since they send more than they receive.