by Kirill Popov

During the Messaging Anti-Abuse Working Group (MAAWG) meeting in early November, a number of ISPs hinted that adoption of Yahoo’s DomainKeys Identified Mail (DKIM) authentication protocol will be the next step in email authentication. While SenderID was a good first step and easy to implement, DKIM will offer greater security and can authenticate mail that has been forwarded through multiple sources.

The difficulty with implementing DKIM is in the requirement to encrypt and decrypt each individual message. These extra steps add some overhead on message processing, which becomes a significant resource drain as volume increases.

Yahoo! is planning to roll out a number of enhancements to its mail service that should promote Domain Keys:

1. It will place a user UI notification about mail that is not signed with DKIM, similar to the current Hotmail notification. Including this “negative” notice will help spur the adoption by most legitimate marketers.
2. Yahoo!'s whitelisting program will require DKIM signed mail and will use the cryptographic key as the basis of white listing, rather than the IP from which the message was sent.
3. DKIM signed mail may clear through some content filters and should have an easier time being delivered into the inbox.

DKIM is gaining momentum, with some real advantages looming on the horizon. Time will tell how quickly and widely the market adopts this authentication approach.

Following are links to related articles on email authentication initiatives:

• Authentication and Accreditation: State of the Industry
• Direct from the Email Authentication Summit 
• Microsoft Adds Hotmail/MSN Mail UI Warning for Emails Not Authenticated by Sender ID