What Is Mailu?

Updated

Mailu is a full-featured mail server delivered as a set of Docker images. It is free and open-source software, and it deliberately avoids proprietary components and unrelated groupware features. It fits people who want to run their own mail server that is relatively easy to set up and maintain, without assembling every component by hand.

What Mailu actually is

Mailu packages the pieces of a working mail system into Docker images that you run together. According to the project's own description, it is "a simple yet full-featured mail server as a set of Docker images," and it is "free software (both as in free beer and as in free speech)." The stated goal is to give people an easily set-up, easily maintained, full-featured mail server while not shipping proprietary software or unrelated features often found in popular groupware.

That last point matters when you compare it with groupware suites. Mailu is not trying to be a calendar, file-sync, or chat platform. It is a mail server, and its feature list stays inside that boundary.

Main features

The project lists these capability areas:

  • Standard email server — IMAP and IMAP+, SMTP and Submission, with auto-configuration profiles for clients.
  • Advanced email features — aliases, domain aliases, custom routing, and full-text search of email attachments.
  • Web access — multiple webmails and an administration interface.
  • User features — aliases, auto-reply, auto-forward, fetched accounts, and managesieve.
  • Admin features — global admins, announcements, per-domain delegation, and quotas.
  • Security — enforced TLS, DANE, MTA-STS, Let's Encrypt integration, outgoing DKIM, an anti-virus scanner, Snuffleupagus, and blocking of malicious attachments.
  • Antispam — auto-learn, greylisting, DMARC and SPF handling, and anti-spoofing.
  • Freedom — all FOSS components, no tracker included.

How it is deployed

Mailu runs on Docker. The documentation covers two main paths:

  • Docker Compose setup, with documented Docker Compose requirements.
  • Kubernetes setup.

There is also a configuration reference, guidance on setting up your DNS, using an external reverse proxy, and changing the database back-end. Administration topics include maintaining a server, the web administration interface, spam filtering, a command-line tool, and a RESTful API.

Because the documentation is written as part of the repository and evolves with it, you should read the version of the docs that matches the Mailu version you are running.

Who it is for

Mailu suits you if:

  • You want to self-host email and are comfortable running Docker.
  • You want a mail server rather than a full collaboration suite.
  • You value an all-FOSS stack with no tracker.
  • You want a documented path for DNS, TLS, antispam, and administration instead of wiring each piece yourself.

It is probably not the right fit if you want a hosted service with no server to operate, or if you need calendar, contacts, and file sharing bundled in the same product.

Getting oriented

If you are evaluating Mailu, the project provides a demonstration server with instructions for connecting to it and adding domains, plus a features-and-screenshots section and an FAQ. A practical first pass is to read the general concepts, then the setup section for your chosen deployment model (Docker Compose or Kubernetes), and then the DNS and reverse-proxy configuration pages, since mail delivery and TLS depend on those being correct.