The Anti-Spam Technical Alliance (ASTA), whose members include Yahoo, Microsoft, EarthLink and AOL, yesterday issued technical recommendations and a guide to best practice to help ISPs and businesses counteract spam.

The recommendations focus on solving the problem of email forgery by eliminating domain spoofing to help prevent ISPs and their customers from being sources of spam.

To combat the threat of email address forgery, ASTA recommends authenticating senders based on IP addresses, and content signing via public/private key pairs.

Other recommendations include tighter control on mailboxes and email providers, and a crackdown on email address harvesting.

Users should also be advised in the implementation of security tools such as firewalls and antivirus software.

"We are laying out clear best practices and 'good neighbour' policies that will help change the rules of the game on spammers once and for all," said Brad Garlinghouse, vice president of communication products at Yahoo, in a statement.

Ryan Hamlin, general manager of the anti-spam technology and strategy team at Microsoft, added: "Our aim with this proposal is to help lay out a clear framework for the industry as we continue to work together to end the spam business and put our customers back in control of their inboxes."

A PDF of the ASTA proposals can be downloaded here.