Internet heavyweights have unveiled plans to get tough on spam, with the introduction of new email sender authentication products.

Microsoft and Yahoo have teamed up with email management firm Sendmail to stamp out spam, domain spoofing and phishing.

Bill Gates, chairman and chief software architect at Microsoft, outlined the software giant's approach to reducing email spam during his keynote speech at the RSA Conference in San Francisco, while Yahoo said it will start testing its DomainKeys cryptographic authentication solution with Sendmail in March.

Sendmail will also develop and distribute sender authentication technologies to customers and the open source community, and work with Microsoft and Yahoo to bring products to market.

Gates outlined his plans for "caller ID for email", a technology to verify that the origin of each email message is the internet domain that it claims.

With the elimination of domain spoofing, legitimate senders will be able to protect their domain names and reputations and help recipients identify and filter junk emails, said Gates.

But email senders will need to register the IP addresses of their outgoing email servers with the internet Domain Name System (DNS) to do this.

Yahoo's recently unveiled DomainKeys will provide a similar mechanism, by using public/private key cryptography to generate a signature in the header of the email message.

When an email message is received from a particular domain, the receiving system verifies the signature with the sender's public key that is published in the public DNS.

If it cannot be verified the identity of the sender is not validated, and the receiving company's local anti-spam policy comes into force.