There's a page up for information related to Caller ID for E-Mail.
From the page:
Caller ID for e-mail would verify that each e-mail message originates from the Internet domain it claims to come from. Eliminating domain spoofing will help legitimate senders protect their domain names and reputations, and help recipients more effectively identify and filter junk e-mail.
You can send comments on the specification to firstname.lastname@example.org.