Mailu

Mailu bundles SMTP, IMAP, webmail, an admin panel and spam filtering into containers for running mail on your own domains.

7.6k stars, 1k forks Python On GitHub since January 2016

Visit website View on GitHub How to run it

Mailu at a glance

Open sourceYes, MITNo paid parts in the repository
Health76 of 100Actively developed
Self-hostingDockerCompose file, 1 service
Interface20 languagesIncluding English, German and French
Issue repliesWithin ~9 hoursMedian first reply; 47% of recent issues answered

What is Mailu?

Mailu is a mail server distributed as a set of Docker images. It covers IMAP and SMTP with submission and auto-configuration profiles for clients, aliases and domain aliases, custom routing, and full-text search that reaches into attachments. Users get webmail, auto-reply, forwarding, fetched accounts, managesieve and passkey sign-in, while administrators get per-domain delegation, quotas and announcements. Security features include enforced TLS, DANE, MTA-STS, Let's Encrypt certificates, outgoing DKIM, an anti-virus scanner and blocking of malicious attachments. Antispam handles greylisting, DMARC, SPF and auto-learning. The project ships only free software components and no trackers.

Good fit if

  • You want hosted-mailbox features such as webmail, aliases and quotas on infrastructure you control.
  • Several domains need separate administrators, and you prefer managing them through a web panel rather than config files.
  • Your clients should authenticate with OAuth 2.0 or passkeys instead of long-lived passwords.

Look elsewhere if

  • You prefer configuring everything in plain files without a web admin: docker-mailserver.
  • You only need outgoing mail from applications: Postal.
  • You want a single install script that also handles DNS on a dedicated machine: Mail-in-a-Box.

Before you adopt it

Mailu uses the MIT license, and its README states that every bundled component is free software compatible with it; no paid parts were found in the repository. The project is owned by the Mailu organization, but one developer wrote about 92% of the 225 commits from the last 90 days, so work depends heavily on that person. The latest release is 2024.06.67, published in October 2026. Deployment needs Docker, and you remain responsible for DNS records and sender reputation. A public demo server lets you try it before installing.

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 Mailu yourself

One-click install

Not listed in the app catalogs of Umbrel, YunoHost, TrueNAS, Unraid, CasaOS, Runtipi, Proxmox VE Helper-Scripts and Coolify.

Ways to install

Docker files
Dockerfile or compose file in the repository
Compose file
docs/docker-compose.yml: 1 service
Setup effort
1 of 5, judged from the compose file
Kubernetes
No Helm chart in the repository
Desktop and mobile
No app builds in GitHub releases
Interface languages
20 languages, including English, German, French, Spanish, Portuguese, Dutch, Polish, Russian, Ukrainian and Japanese
Show all 20

Basque, Catalan, Chinese, Czech, Danish, Dutch, English, French, German, Hebrew, Hungarian, Japanese, Norwegian Bokmål, Persian, Polish, Portuguese, Russian, Spanish, Swedish, Ukrainian

Install instructions: mailu.io or the README on GitHub.

Mailu health: is it still maintained?

76 of 100, actively developed

Release rhythmEvery ~5 daysLatest: 2024.06.68, 8 November 2026
Issue repliesWithin ~9 hoursMedian first reply; 47% of recent issues answered
Bus factorHigh riskThe most active of 4 authors wrote 94% of recent commits
  • Activity
    259 commits in the last 90 days, the latest on 10 November 2026.
    29 / 30
  • Contributors
    4 people wrote the latest 100 commits; the most active wrote 94% of them.
    6 / 20
  • Releases
    15+ releases in the last 12 months; the latest, 2024.06.68, on 8 November 2026.
    19 / 20
  • Replies to issues
    Maintainers answered 47% of recent issues, with a median first reply after 9 hours.
    16 / 20
  • Security practices
    OpenSSF Scorecard 5.8 of 10.
    6 / 10

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

Mailu 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 advisories10 published2 critical, 5 high; all list a fixed version
OpenSSF Scorecard5.8 of 10How the project is built and released
Security policyPartlyExplains how to report a vulnerability

Latest advisories

All 10 advisories on GitHub

What each Scorecard check found

  • Code review10 / 10Changes are reviewed before merge
  • Dangerous workflows10 / 10No risky patterns in GitHub Actions
  • Maintained10 / 10Steady commits and issue activity in the last 90 days
  • Binary files9 / 10A few compiled binaries are checked into the repository
  • License file9 / 10A license file is present, but not where tools look for it
  • Pinned dependencies5 / 10Some dependencies use fixed versions
  • Security policy3 / 10A security policy exists but leaves things out
  • Best-practices badge0 / 10No OpenSSF Best Practices badge
  • Fuzzing0 / 10No fuzz testing found
  • Static analysis0 / 10No static analysis found
  • 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 Mailu are left out.

Mailu license: is it open source?

Mailu uses MIT, an open-source license approved by the OSI.

  1. January 2016First published on GitHub.
  2. TodayMIT.

Mailu for developers

Written in

  • Python 79%
  • HTML 11%
  • JavaScript 3%
  • Shell 2%
  • PHP 2%
  • Other 3%

Getting involved

Contributing guideYesCONTRIBUTING.mdOpen issues54On GitHub
Authors, 90 days4Of the latest 100 commits
DonationsCOMMUNITY_BRIDGEListed on GitHub

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

Alternatives to Mailu

  • Maddy Mail ServerComposable all-in-one mail server. 73 health · GPL-3.0 · 6.1k stars
  • Mailcowmailcow: dockerized - + = 74 health · GPL-3.0 · 13.8k stars
  • docker-mailserverProduction-ready fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.) running… 80 health · MIT · 19.7k stars
  • Stalwart Mail ServerAll-in-one Mail & Collaboration server. Secure, scalable and fluent in every protocol (IMAP, JMAP, SMTP,… 57 health · Unidentified license · 15.9k 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

All 17 projects in Email servers & webmail

Questions about Mailu

Is Mailu open source?

Yes. Mailu is published under MIT, an OSI-approved open-source license.

Is Mailu still maintained?

Its health score is 76 of 100 (actively developed). It had 259 commits in the last 90 days, the latest on 10 November 2026, and its latest release came out on 8 November 2026.

How do I run Mailu?

You can run it with Docker. The README on GitHub has the exact steps.

What is Mailu written in?

Mailu is written mainly in Python (79% of the code), with HTML (11%), by GitHub’s count of the repository.

What languages is Mailu available in?

The repository has interface translations for 20 languages, including English, German, French, Spanish, Portuguese, Dutch, Polish and Russian.

What are the alternatives to Mailu?

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