Enigmail

Rated 5 out of 5 stars

by bananape on March 2, 2016 · permalink

Although it admitedly has some quirks regarding the interface this extension works quite well. Does what its supposed to including HTML support (since PGP/MIME is enabled by default from 1.9 on)
Quote from the Enigmail 1.8 Manual (p. 49):
"HTML messages cannot be handled well, if you are using the OpenPGP inline format. The PGP/MIME format, however, can deal flawlessly with HTML messages. Unfortunately, not every mail client can interpret the PGP/MIME format."

Another plus: Thunderbird Conversations is compatible with Enigmail.