OnionMail is an open source SMTP/POP3 compatible mail server with some functions designed for Tor hidden services. OnionMail use filesystem cryptography and some extended functions. This server also allows you to use the email in the tor network without losing the ability to communicate with the Internet.

How it works:
Usually other mail systems all mail messages pass through different SMTP servers often the connection is not encrypted.
With OnionMail the connection is always encrypted and the server does not saving data to disk. Only the recipient's server stores the messages.
The message files into the server are encrypted with asymmetric key, which is encrypted with the password of the user and the server keys. In the event of theft, the system does not reveal any sensitive data.
It always advisable to use PGP or GPG to encrypt e-mail messages.
When a message is sent from the Internet it passes through the server Enter / Exit. These servers are the entry and exit nodes of Tor for e-mail. The user can choose which node to use to communicate to the internet.
Spam is short-lived because there are the custom blacklists. So each user can set their own spam filters.
All servers are federated to create a check system for SSL server certificates.
With systems like this X-Keyscore and similar technologies have big problems to intercept your mail messages.


See OnionMail.info to get more informations.