In a combined effort to fight spam, Yahoo and Cisco Systems have announced an authentication technology designed to combat e-mail forgery by verifying the address of origin of e-mail messages. The combined technology solution will be called DomainKeys Identified Mail (DKIM), Domain-Keys from Yahoo And Internet identified mail from Cisco. DKIM is a unified e-mail authentication proposal that enhances consumer protection from e-mail forgery, and enhances accountability for spam and phishing scams.

This approach uses public key cryptography to allow users to verify and maintain message integrity, and identifies legitimate messages.

DKIM uses the Internet's Domain Name System (DNS) in the same manner as DomainKeys. DKIM also leverages Identified Internet Mail's header-signing technology, ensuring signature consistency as messages are sent through the network.

The benefits of signing e-mail using DKIM can be significant for companies that commonly send transactional e-mail to consumers, such as banks, utilities, and e-commerce services.

Yahoo has developed and implemented DomainKeys technology in an effort to address the growing threat of e-mail forgery. DomainKeys leverages public-key cryptography to verify the sender of an e-mail message at the domain level. A sending system uses a private key to generate a signature and inserts the signature in the e-mail header; and the receiving e-mail system uses the public key, published in the Internet's Domain Name System, to verify the signature of the e-mail.