A number of weeks ago someone pointed me to darkmail which was started by the same people who ran Lavabit before it shutdown.
I thought “this sounds great!… if it works”
Sadly I do not know how it works without reading the specification. The website is pretty bare, as is the wikipedia article (at the time of this writing). But I have used, and have a general understanding of, PGP and S/MIME. Both of which have not seen really great adoption, and remain pretty niche products.
There was an interesting post on the planet Mozilla by Joshua Cranmer, who works on various parts of the Mozilla Mail module, gave his opinion on why e-mail security failed. While I have not come across many of the problems (which I probably would if more people used it) he points out, one issue he does point that I think is pretty major is the fact that you cannot do server-side searching and SPAM filtering on a pure end-to-end encryption model.
So it would be interesting to see whether and how Darkmail solves this issue. Or whether we would have to accept sacrifices in security for more usability.