EarthLink Inc. and Yahoo Inc. said Monday they would begin tests of a new anti-spam technology that encodes digital signatures into customers' e-mail as a way to separate legitimate messages from unwanted spam.
Developed by Yahoo, the technology is one of several emerging standards that seeks to flush out fake addresses used by spammers to slip through content filters. It would be invisible to regular Internet users.
Yahoo's DomainKeys embeds outgoing messages with an encrypted digital signature matched to a signature on the server computer that sends the message.
Internet providers could check the signatures on incoming messages and block those that do not match up, though they are more likely to use it alongside other anti-spam technologies.
Internet experts generally agree that DomainKeys provides a higher level of security than a Microsoft Corp.-backed standard known as SenderID, but is more difficult to implement and requires about 10 percent more computing power to process.
Google Inc.'s Gmail and Indian Internet provider Sify have already begun using DomainKeys.