Mailpile provides a nice looking webmail interface suitable for use on desktop or mobile clients. It has good support for email encryption and makes that quite an simple process. At present it's usable but still has a few bugs and limitations. If you need a fully functional email client with comprehensive encryption support then either use Mutt or Thunderbird/Icedove.
An advantage of this type of webmail is that /it keeps your GPG keys off of any mobile devices/ so that if you lose your phone, or it gets stolen, then your email might still not be compromised.
One down side is that this appears to be a single user system, so if you have multiple users on your Freedombone server only the administrator will actually be able to use mailpile.
* Setup
If you're viewing your mail domain site on a mobile device via OrFox then make sure you allow the domain in the NoScript settings.
Enter a password and store it within a password manager.
Click on the *Privacy and Security* button.
Scroll down and select *Save Settings*. Don't click on the Tor button.
Under *Sending Mail* select *local* or if you need to proxy outgoing email through your ISP's server select *SMTP/TLS* and enter the details, then click *Next*.
Under *Receiving files* select *IMAP*, the domain as *localhost*, port *143*, your username and password, then click *Next*. Astute readers may well be concerned that IMAP over port 143 is not encrypted, but since this is only via localhost communication between the Mail Transport Agent and Mailpile doesn't travel over the internet and port 143 is not opened on the firewall so it's not possible to accidentally connect an external mail client insecurely.
Under *Security and Privacy* either select your existing encryption key or if you only get the option to create a new one then do so, then click *Add* or *Save*.
