The other day I mentioned that one long term solution to spam might be a widespread system of digitally signing emails so that the sender’s identity can be verified (basic web of trust public key cryptography stuff). It looks like Yahoo has proposed an anti-spam system that proposes exactly that. With any such system, you’d treat signed emails as trusted, and unsigned emails as suspect, but if it sees wide adoption, you would eventually be able to treat any unsigned email as spam. Now I’d like to see the technical specifications for Yahoo’s DomainKeys proposal published somewhere online so that the email and crypto geniuses can start poking holes in it before it’s actually deployed.