EBay and PayPal have partnered with Gmail to fight against fraudulent e-mails and phishing attacks. By means of the DomainKeys and DomainKeys Identified Mail (DKIM) authentication technology, Google is capable of preventing the delivery of fraudulent eBay and PayPal messages to Gmail users. The project targets Gmail, eBay and PayPal customers throughout the world.

DomainKeys technology enables internet service providers to assess whether messages are real or not and decide if they should reach a customer's inbox. DomainKeys and DKIM make use of cryptography to verify the domain of the sender. It allows e-mail providers to validate an e-mail's originating domain.

The first version of DKIM, released in 2005, was the result of a collaboration between numerous industry players, including Alt-N Technologies, AOL, Brandenburg InternetWorking, Cisco, EarthLink, IBM, Microsoft, Sendmail, StrongMail Systems, Tumbleweed, VeriSign and Yahoo!.