Stalwart

Against what buyers need

Email server: covers 82% of the checklist. One Rust server that speaks SMTP, IMAP, JMAP, POP3, CalDAV, CardDAV and WebDAV, with its own spam filter that trains itself, DKIM, SPF, DMARC and ARC, Sieve, LDAP or OIDC login with 2FA, a web admin and an MTA queue with throttling. It has no webmail or ActiveSync, so pair it with Roundcube, and encryption covers mail at rest with each user's S/MIME or OpenPGP key. Multi-tenancy, the AI spam classifier and undelete are in the paid Enterprise edition. Missing: webmail.

Judgement

What it is

Complete system

What it does

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.

Adopt it when

You want to self-host email, calendars and contacts in one modern binary instead of assembling Postfix, Dovecot and Rspamd.

Watch out

Some features are reserved for the paid Enterprise edition, it only recently reached 1.0, and running any mail server means owning deliverability.

Ready for

Usable

Runs as

Self-hosted server

Built with

Rust, RocksDB and PostgreSQL

How established

Established: started 3 years ago, latest release v1.0.3.

What the license allows

GitHub could not read the license. Check it in the repository before reusing any code.

Judged on 2026-11-06 from the project's README and GitHub data. The license and age lines are worked out directly.

Compare Stalwart

Built from

Follow it down: Stalwart → Rust → runs on a microchip

How compilers were built, back to punched paper tape

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