Yahoo originally developed the technology to reduce the amount of spam coming from spoofed e-mail addresses (define), which in turn leads to phishing attacks on personal and confidential information.
"Yahoo Mail understands that online security is vital to consumers, and through our development and implementation of the DomainKeys authentication solution, we are actively helping to protect consumers from threats like e-mail spoofing and identity theft," Brad Garlinghouse, Yahoo vice president of communications products, said in a statement.
The announcement was one of several made by the portal, which is facing fierce competition from upstarts like Google and long-time threats like Microsoft. Also launched Monday was an increase to the storage space for Yahoo members, from 100 MB to 200MB with 10MB attachments. Yahoo premium customers get 2GB of space and 20MB for file attachments, a move prompted by Google's 1 GB Gmail service.
DomainKeys is similar to the controversial Sender ID for E-Mail technology from Microsoft in that it checks to make sure e-mail is coming from the person or company it claims. It inserts a digital signature into e-mail headers to confirm the source and guarantee the message wasn't changed in transit.
Sender ID, on the other hand, is an IP-based answer to authentication that checks the Purported Responsible Address (PRA) header information against a list of known, and accepted, domains.