Shame, really. I love distributed P2P applications built around dumb, simple techniques or tools. Super complex abstractions are useful but as a project creator it's difficult to rely on new technology if you can't support it yourself.

Email is one of those dumb, old systems I've often wanted to push a ton of stuff into. Ala' the days of Twitter and SMS, The role of email and how widely it's used just seems perfect for dumb distributed applications... if not for the issues you cited.