Yahoo users can feel a little bit more secure when receiving email from eBay and Paypal after today’s yodel: Say goodbye to eBay and PayPal fraudsters.

We’ve teamed up with eBay and PayPal to become the first Web mail service to block the delivery of unauthenticated eBay and PayPal emails, reducing your risks of receiving phishing scams or fraudulent emails. Our weapon is a technology Yahoo! spearheaded called DomainKeys, which uses cryptography to verify the domain of the sender.

This is similar to the discussions in the past about Hotmail delivery issues and how to resolve them. Publishing your SPF and SENDER ID will help your messages deliver at a number of ISPs, similar to the Domain Keys implementation at Yahoo!

This is the first major announcement of this kind, be prepared for more to follow by authenticating your mail now. Not just your commercial or transactional email but also your Corporate email.