Yahoo and Cisco are jointly working on a new e-mail authentication system, it has been revealed this week. Both companies are combining their anti-spam technologies into the effort, which they are calling DomainKeys Identified Mail (DKIM). The technology will utilise Yahoo's DomainKeys authentication technology and Cisco's Internet Identified Mail in an effort to reduce the amount of spam spread across the Internet.

It wasn't immediately clear how the new technology would fit in with the companies' prior work on authentication systems, however. Yahoo has already implemented DomainKeys into its Yahoo Mail service and offers the technology royalty-free to other industry players.

The Sunnyvale, California, Internet company said that it receives more than 350 million messages a day signed by DomainKeys, but did not say whether it plans to replace the technology once DKIM becomes available.

As for Cisco, it released an open source implementation of Identified Internet Mail late last year.