Proton Mail vs Stalwart
Proton Mail and Stalwart are both email server software. Proton Mail is a commercial product from Proton AG. Stalwart is open source under a license set out in its repository, with 16k GitHub stars.
Which to pick
- Pick Proton Mail when
- Privacy is your first concern and you want encrypted email, especially between Proton users.
- Pick Stalwart when
- You want to self-host email, calendars and contacts in one modern binary instead of assembling Postfix, Dovecot and Rspamd.
Side by side
End-to-end encrypted email from Switzerland, bundled with Proton's calendar, drive, VPN and password manager.
A Rust mail and collaboration server that handles SMTP, IMAP, POP3 and JMAP, plus CalDAV, CardDAV and WebDAV, with built-in spam filtering, DKIM, DMARC and a web admin.
Desktop email clients need the paid Bridge app, and encryption limits server-side search and integrations.
Some features are reserved for the paid Enterprise edition, it only recently reached 1.0, and running any mail server means owning deliverability.
Production-ready
Usable
Cloud service, desktop app and mobile app
Self-hosted server
Not published
Rust, RocksDB and PostgreSQL
Closed source, sold by Proton AG
Open source, license unclear on GitHub
Closed source: you use it under the maker's terms and cannot change or resell the code.
GitHub could not read the license. Check it in the repository before reusing any code.
12k Wikipedia readers a month on phones
16k GitHub stars
Not known
Established: started 3 years ago, latest release v1.0.3.
Other comparisons
More email servers and webmail
Both sides were judged on 2026-11-03 from makers' descriptions, Wikipedia, READMEs and GitHub data. License, age and popularity lines are worked out directly.