The makers of the encrypted e-mail client WhiteOut are doing a crowdfunding campaign. I have tried the current version of their software and I am impressed how easy it is to use. WhiteOut lets you use OpenPGP encryption (one of the forms of encryption that are even for the NSA very hard to crack) and removes much of the technical difficulties.
It is still missing a number of features, e.g. you cannot create new folders and you cannot easily move your mail out of the Inbox with a GMail-like “archive” function (a must-have for me and the main reason why I use Thunderbird at the moment), but maybe the crowdfunding money goes some way to help along development. I encourage everyone to contribute!