OnionMail is a project that hasn't gotten its deserved publcity. Its supposed to be a Mixmaster-style service built on Tor. Its an anonymous mail server network which supports exiting messages. It doesn't add high latency guarantees of its own but it has a few benefits over using a mail service HS.
The best technical intro I found:
- Makes pseudonymous mail account creation easier and safer than conventional services - in client registration possible.
- Integrates with Icedove
- Bi-directional communication possible enitrely inside the Tor network o with clearnet addresses
- You don't have to trust their crypto implmentations if you use your own GPG key
- Debian packages available via their repo
- Written in memory safe Java
- I tried it out and its designed to only use a local Tor instance
- Would need OpenJDK (not a big deal as so would I2P)
I am thinking about contacting them about changes we would like to see to improve compatibility with Whonix and UX. They made a GUI install wizard for TAILS but its outdated.
Another interesting software project they have is NTU which transparently directs traffic over SOCKS proxy servers to evade Tor bans. Interesting but haven't tried it yet.