See my other comment about Virtru and allowing for self-hosted keys. We also don't host the content, so different laws apply..I think znelson commented on that somewhere in the thread already.
So as of this moment, you can't keep the keys yourself. Our technology absolutely allows for self-hosted keys. We do have private key managers being developed, which we intend to open source, and be for private use. It will be an option for the those that want the responsibility of keeping the keys safe, and also address your concern.
Encryption has been used in the past to keep emails secure from surveillance(PGP), but it has always been cumbersome to setup and use on both ends. Virtru's focus has been to make powerful encryption available to everyone by making it easy to use and with the services you and those you communicated with already use. Right now we have Chrome/Firefox support as well as an iPhone app...but many other clients soon.
Not exactly. Virtru customer-hosted keys are PGP wrapped before they go over the wire via TLS.