Bitmessage will do the job.
will it???
i tried it and it took forever to gen an address. then those funky rules around when emails get sent with proof of work being done on the client, I don't want my cell phone's battery getting drained just so I can send a quick email/msg. the cost is too high to use in my opinion at the moment
and as far as i can tell there is no way to create mail mining nodes so one could offer an ad funded service like gmail.
the client looks like crap...
b/c it does not interface with the current system it will have adoption issues, since most people are not paranoid about their email, unless they have a reason to be paranoid