Open-source email providers

3 email providers whose code is public under an OSI-approved license, rated for privacy with evidence. Picks first, then by score.

1. Kolab Now Grade C

   Paid email and groupware service from Apheleia IT in Switzerland, built on the open-source Kolab platform, with calendars, contacts, files and video calls.

   Runs on the open-source Kolab platform, and the terms state that all software used is free software. Source code

2. Disroot Grade D

   Volunteer-run platform from the Netherlands offering email and other open services.

   Runs only free and open-source software such as Postfix, Dovecot and Roundcube. Deployment roles are published at git.disroot.org. Source code

3. Thundermail Grade D

   Paid email, calendar and contacts service from MZLA Technologies, the Mozilla subsidiary that makes Thunderbird. Built on the Stalwart mail server, with data hosted in Germany. In beta and open only by invitation from a waitlist.

   The account service, webmail and deployment code are published under MPL-2.0. The mail server is Stalwart, which is AGPL-3.0 with some enterprise features under a source-available license. Source code

Compare all 44 email providers, open source or not.