eBay, PayPal and Yahoo have begun collaborating to keep Yahoo Mail customers safe from phishing by using Yahoo's Domain Keys technology in the U.S. to block e-mail messages that claim to come from eBay or PayPal. Yahoo expects to make the system available globally in the next few weeks.
Domain Keys was developed by Yahoo as a way to make sure that e-mail comes from where it says it comes from. In May, the Internet Engineering Task Force adopted the DomainKeys Identified Mail, which incorporates Cisco's Identified Internet Mail system, specification as a Proposed Standard. With the aim of fraud and theft, phishers use fake e-mails to convince the receiver that information is required for their eBay, PayPal or similar account and to click on links that lead to phony Web sites where they then typically enter personal or account information and passwords.
News source: InformationWeek