Stalwart Mail Server

A Rust mail and collaboration server covering SMTP, IMAP, JMAP, CalDAV, CardDAV and WebDAV, with spam filtering and a web admin.

15.9k stars, 1k forks Rust On GitHub since March 2023

Visit website View on GitHub How to run it

Stalwart Mail Server at a glance

Open sourceUnclear licenseSome paid parts in the repository
Health57 of 100Actively developed
Self-hostingDocker, Desktop appsOne-click in Umbrel, TrueNAS and 3 more
AppsLinux, macOS, Windows, including ARMBuilds in GitHub releases
InterfaceEnglish onlyNo translation files found
Issue repliesNo repliesNone of the recent issues got an answer from the team

What is Stalwart Mail Server?

Stalwart combines a mail server and a groupware server in one Rust program. It speaks SMTP, IMAP, POP3 and JMAP for email, CalDAV and CardDAV for calendars and contacts, and WebDAV for files. Built-in protection covers DKIM, SPF, DMARC, DANE and MTA-STS, plus a spam filter with statistical and optional AI classifiers. Mailboxes can be encrypted at rest with OpenPGP or S/MIME. Storage backends include RocksDB, PostgreSQL, MySQL, SQLite and S3-compatible services, and clusters can scale across many nodes. A web interface handles accounts, domains, queues, reports and logs.

Good fit if

  • You want to replace a hosted email and calendar suite with one server you run yourself.
  • You need multi-tenancy, LDAP or OpenID Connect sign-in, and clustering.

Look elsewhere if

  • You want a plainly MIT-licensed mail stack built from Postfix and Dovecot: docker-mailserver.
  • You only need outgoing and incoming mail for applications: Postal.

Before you adopt it

The license could not be identified, so Stalwart is not open source by the OSI definition as far as the data shows; read the license files before deploying it. Some parts are paid and fall under a separate licence, LICENSES/LicenseRef-SEL.txt, so check whether the features you need fall under it. Outside contributions require signing a contributor license agreement (CLA). About 88 percent of recent commits come from one developer, so the project depends heavily on that person. Docker images and builds for Linux, macOS and Windows are available.

Drafted with AI from the project's README and repository data, then checked against that data on 7 November 2026. Report a correction

How to run Stalwart Mail Server yourself

One-click install

Not listed in YunoHost, CasaOS and Runtipi. Checked against each panel’s app catalog on 12 November 2026.

Ways to install

Docker files
Dockerfile or compose file in the repository
Docker image
stalwartlabs/stalwart: 3.4M pulls · x86-64, ARMv6, ARMv7, ARM64 · 124 MB downloadAlso ghcr.io/stalwartlabs/stalwart
Compose file
None in the repository
Setup effort
Not rated: no compose file to judge from
Kubernetes
No Helm chart in the repository
Packages
Arch Linux and Nix versions on Repology
Desktop and mobile
Builds for Linux, macOS, Windows, including ARM in GitHub releases
Interface languages
English only

Install instructions: stalw.art or the README on GitHub. Docker images and packages are checked weekly.

Stalwart Mail Server health: is it still maintained?

57 of 100, actively developed

Release rhythmEvery ~7 daysLatest: v1.1.0, 9 November 2026
Issue repliesNo repliesNone of the recent issues got an answer from the team
Bus factorHigh riskThe most active of 4 authors wrote 88% of recent commits
  • Activity
    179 commits in the last 90 days, the latest on 9 November 2026.
    27 / 30
  • Contributors
    4 people wrote the latest 100 commits; the most active wrote 88% of them.
    6 / 20
  • Releases
    15+ releases in the last 12 months; the latest, v1.1.0, on 9 November 2026.
    19 / 20
  • Replies to issues
    Maintainers answered 0% of recent issues.
    0 / 20
  • Security practices
    OpenSSF Scorecard 4.9 of 10.
    5 / 10

Read from GitHub on 12 November 2026. How the score works

Stalwart Mail Server security

Security advisories are the vulnerabilities the maintainers disclosed on GitHub, with the versions that fix them; many advisories can mean careful disclosure as much as weak code. OpenSSF Scorecard checks how a project is developed and released: reviews, protected branches, pinned dependencies, signed releases. It does not audit the code itself.

Security advisories5 published1 critical, 2 high; all list a fixed version
OpenSSF Scorecard4.9 of 10How the project is built and released
Security policyYesExplains how to report a vulnerability
Signed releasesPartlyOnly some downloads can be checked against a signature

Latest advisories

All 5 advisories on GitHub

What each Scorecard check found

  • Binary files10 / 10No compiled binaries checked into the repository
  • Dangerous workflows10 / 10No risky patterns in GitHub Actions
  • Dependency updates10 / 10A tool such as Dependabot keeps dependencies up to date
  • License file10 / 10A license file is present
  • Maintained10 / 10Steady commits and issue activity in the last 90 days
  • Security policy10 / 10Explains how to report a vulnerability
  • Signed releases8 / 10Some releases are signed
  • Contributor base6 / 10Contributors come from a few organizations
  • Known vulnerabilities2 / 10Some open known vulnerabilities in the code or its dependencies
  • Best-practices badge0 / 10No OpenSSF Best Practices badge
  • Branch protection0 / 10The main branch has no protection rules
  • Code review0 / 10Changes are merged without review
  • Fuzzing0 / 10No fuzz testing found
  • Pinned dependencies0 / 10Dependencies are not pinned to fixed versions
  • Static analysis0 / 10No static analysis found
  • Tests in CI0 / 10No tests found on pull requests
  • Token permissions0 / 10CI tokens have broad write rights

Advisories read from GitHub on 12 November 2026. From the OpenSSF Scorecard of 9 November 2026; checks that do not apply to Stalwart Mail Server are left out.

Stalwart Mail Server license: is it open source?

We could not identify the license of Stalwart Mail Server. Check the repository before you build on it. Some features sit under a separate paid license inside the same repository. Contributors sign a contributor license agreement, which lets the owner relicense their work later.

  1. March 2023First published on GitHub.
  2. TodayUnidentified license, with paid parts: separate license LICENSES/LicenseRef-SEL.txt. A contributor license agreement is required.

Stalwart Mail Server for developers

Written in

  • Rust 99%
  • Python <1%
  • HTML <1%
  • JavaScript <1%
  • Shell <1%
  • Other <1%

Getting involved

Contributing guideYesCONTRIBUTING.mdOpen issues39On GitHub
Authors, 90 days4Of the latest 100 commits
Donations2 waysGitHub Sponsors, Open Collective

Language shares are GitHub’s count of the code in the repository.

Alternatives to Stalwart Mail Server

  • docker-mailserverProduction-ready fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.) running… 80 health · MIT · 19.7k stars
  • MailuInsular email distribution - mail server as Docker images 76 health · MIT · 7.6k stars
  • Maddy Mail ServerComposable all-in-one mail server. 73 health · GPL-3.0 · 6.1k stars
  • Mail-in-a-BoxMail-in-a-Box helps individuals take back control of their email by defining a one-click, easy-to-deploy… 53 health · CC0-1.0 · 15.5k stars
  • Mailcowmailcow: dockerized - + = 74 health · GPL-3.0 · 13.8k stars

All 17 projects in Email servers & webmail

Questions about Stalwart Mail Server

Is Stalwart Mail Server open source?

We could not identify its license, so treat it as not open source until you have checked the repository.

Is Stalwart Mail Server still maintained?

Its health score is 57 of 100 (actively developed). It had 179 commits in the last 90 days, the latest on 9 November 2026, and its latest release came out on 9 November 2026.

How do I run Stalwart Mail Server?

You can run it with the Docker image stalwartlabs/stalwart, as an app for Linux, macOS, Windows, including ARM and in one click from Umbrel, TrueNAS, Unraid and 2 more. The README on GitHub has the exact steps.

What is Stalwart Mail Server written in?

Stalwart Mail Server is written mainly in Rust (99% of the code), by GitHub’s count of the repository.

What are the alternatives to Stalwart Mail Server?

Close alternatives in the Email servers & webmail category include docker-mailserver, Mailu, Maddy Mail Server.