All the legislation and regulation in the world has done little, if nothing to staunch the flow of spam into e-mail boxes around the world. One solution to the problem involves some sort of sender authentication, which would move the battle from the recipients’ spam filters back to the IP address and domain levels. That solution just became more promising, as Sendmail, a large e-mail system provider, has announced plans to back both Yahoo’s and Microsoft’s e-mail authentication schemes.
http://arstechnica.com/news/posts/1077903896.html