Mail-in-a-Box vs Stalwart
Mail-in-a-Box and Stalwart are both email server software. Mail-in-a-Box is open source under CC0-1.0, with 15k GitHub stars. Stalwart is open source under a license set out in its repository, with 16k GitHub stars.
Which to pick
- Pick Mail-in-a-Box when
- You want your own email on a dedicated VPS with as few decisions as possible.
- 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
A setup script that turns a fresh Ubuntu server into a complete mail server with Postfix, Dovecot, Roundcube webmail, Nextcloud contacts and calendars, spam filtering, DNS and TLS.
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.
It takes over the whole machine, allows almost no customisation, and depends on a specific Ubuntu LTS release.
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
Self-hosted server (both)
Python, Shell, Postfix, Dovecot, Roundcube and Nextcloud
Rust, RocksDB and PostgreSQL
Open source, CC0-1.0 (public domain)
Open source, license unclear on GitHub
You can take the code into anything, including a product you sell, with no conditions.
GitHub could not read the license. Check it in the repository before reusing any code.
15k GitHub stars
16k GitHub stars
Established: started 13 years ago, latest release v77.
Established: started 3 years ago, latest release v1.0.3.
Other comparisons
More email servers and webmail
Both sides were judged on 2026-11-06 from each project's README and GitHub data. License, age and popularity lines are worked out directly.