What does mailcow replace?

mailcow is a free alternative to Fastmail ($60/yr).

Is mailcow open source?

Yes. mailcow is licensed under GPL-3.0, an OSI-approved open-source license.

Yes (self-hosted server; web UI).

Yes. mailcow is a server app you run on your own server, and its repository includes Docker files.

A free, open-source alternative to Fastmail. Switching saves $60/yr at list price.

Checked Oct 17, 2026 · How we check

Self-hosted server

Replaces it Active Open source · GPL-3.0 Linux Self-hostable

mailcow/mailcow-dockerized13.6k★last push Oct 15, 2026checked Oct 17, 2026

Running a mail server needs a clean-IP VPS with port 25 open, and deliverability and spam filtering are on you.

Imports your data: built-in IMAP sync jobs pull your mail over from Fastmail

Self-host

Runs on your own Linux server, with Docker files in the repo. Setup docs are on mailcow.email.

What does mailcow replace?: mailcow is a free alternative to Fastmail ($60/yr).
Is mailcow open source?: Yes. mailcow is licensed under GPL-3.0, an OSI-approved open-source license.
Does mailcow run on Linux?: Yes (self-hosted server; web UI).
Can you self-host mailcow?: Yes. mailcow is a server app you run on your own server, and its repository includes Docker files.