Could track-backs or pings from RSS by used on e-mail servers to combat spam and spoofing?

The outgoing mail server to stores a hash or simply the message-id of each message originating locally.

The receiving server, or any along the way, would track-back/ping the originating server (based on MX records) with some unique ID header tag, to see if the message truly originate there.

A simple web service would respond with appropriately information for success and failure.

Sure, there are a range of issues, but perhaps this type of technique could go a long way towards combating spam, and more importantly spoofing.

I’ve built a prototype, using Ruby and CommunigatePro, but need to deploy it in our data center to run real world tests.

Just a thought.