Email, like Google Wave, already is a federated model and you can indeed run it on your own server. Problem it's not practical for people to run servers 24/7 from their home Internet connections. You can remove this burden from people by having a company that hosts everyone's in a data center, but then we're right back at the same place as email: if you get an NSL you have to comply or go under.
So decentralized might be a better way to go. Have you tried https://bitmessage.org/ ?
