Mailu vs docker-mailserver

Mailu and docker-mailserver are the two popular lightweight, MIT-licensed ways to self-host email without committing to a heavyweight suite like Mailcow. Under the hood they cover the same ground — Postfix and Dovecot with a modern antispam layer — so the mail itself behaves similarly. Where they part company is philosophy: Mailu wants to manage your server through a friendly web UI, while docker-mailserver wants you to manage it through configuration files. That single disagreement shapes everything from setup to footprint.

A managed suite vs. a config-file container

Mailu presents itself as a small suite of Docker images with a friendly face. You generate your docker-compose.yml and settings from a web-based setup wizard, then run several coordinated services: an admin app (Flask), a database, the mail daemons, antispam, and bundled webmail. Day to day you manage users, aliases, and domains from a web admin panel, and your users get a webmail login (Roundcube or SnappyMail) without any extra work. It is the gentler on-ramp, especially for people who would rather not live in a terminal.

docker-mailserver takes the opposite stance: one container, no database, no web UI. Everything is driven by a handful of plain files and a setup CLI — you add a mailbox with a single command and edit configuration in your editor of choice. There is no admin dashboard and no bundled webmail; the container is the mail server and nothing else. For people who want to understand every moving part, keep their entire setup in version control, and avoid running a database just to store a handful of accounts, that minimalism is the whole appeal.

Footprint

Because docker-mailserver is a single container with no database and optional antivirus, it is the lighter of the two — roughly 512 MB of RAM with ClamAV switched off, comfortably inside the smallest VPS tiers. Mailu's extra services (the admin app, its database, and webmail) push it to around 1 GB. Neither is heavy next to Mailcow's 6 GB, so both are genuine "small box" options; docker-mailserver just squeezes into an even smaller one.

Managing it day to day

This is the real decision. Mailu's web panel means adding a user, setting a quota, or creating an alias is a few clicks, and non-technical teammates can be given limited access. docker-mailserver expects you to run commands and edit files — setup email add, setup alias add, and friends — which is fast and scriptable if you are comfortable in a shell, and opaque if you are not. If you want to store your mail server's entire configuration in a Git repository and reproduce it exactly, docker-mailserver's file-driven model is purpose-built for that; Mailu keeps more of its state in a database.

Antispam and antivirus

Both ship a serious spam story — Rspamd does the heavy lifting in each — so you are not choosing between "protected" and "unprotected." The difference is again about control surface: Mailu exposes settings and quarantine through its UI, while docker-mailserver expects you to tune Rspamd and toggle ClamAV through environment variables and config files. ClamAV is the main memory hog in either; leaving it off is what gets docker-mailserver down to its 512 MB figure, and the same lever exists in Mailu if you need to trim RAM.

Which to choose

Choose Mailu if you want a web admin panel, a guided wizard, and built-in webmail — the friendlier setup for a small team or anyone who prefers a UI. Choose docker-mailserver if you prefer a single, minimal, transparent container you can fully inspect and keep in version control, and you are happy managing mail from the command line. Both are MIT-licensed and both are genuinely lightweight, so the choice is really about how you like to operate, not about capability.

The deliverability caveat

As with every self-hosted mail server, the software is the easy part. Neither Mailu nor docker-mailserver absolves you of the deliverability work: a clean sending IP, a correct reverse-DNS (PTR) record, and properly configured SPF, DKIM, and DMARC are what actually get your mail into inboxes, and both leave that entirely up to you. Before you pick between the two, make sure your VPS provider allows outbound port 25 and will set a PTR record for your domain — without that, neither tool can deliver, and the Mailu-versus-docker-mailserver question is moot.