Free, open-source alternatives to Fastmail
Paid email with your own domain. 5 apps you can run yourself instead of Fastmail, sorted by how well they replace it. Each one is open source, so your data stays with you.
Stalwart Mail ServerBest match
All-in-one mail server with JMAP, IMAP4, and SMTP support and a wide range of modern features.
Mailcow
Mail server suite based on Dovecot, Postfix and other open source software, that provides a modern Web UI for administration.
Mail-in-a-Box
Turns any Ubuntu server into a fully functional mail server with one command.
Mailu
Simple yet full-featured mail server as a set of Docker images.
Mox
Complete e-mail solution with IMAP4, SMTP, SPF, DKIM, DMARC, MTA-STS, DANE and DNSSEC, reputation-based and content-based junk filtering, Internationalization (IDNA), automatic TLS with ACME and Let's Encrypt, account autoconfiguration, and webmail.
Side by side
| App | Stars | License | Activity | Runs on |
|---|---|---|---|---|
| Stalwart Mail Server | 15,074 | AGPL-3.0 | Rust, Docker | |
| Mailcow | 13,600 | GPL-3.0 | Docker, PHP | |
| Mail-in-a-Box | 15,438 | CC0-1.0 | Shell | |
| Mailu | 7,551 | MIT | Docker, Python | |
| Mox | 5,896 | MIT | Go |
Why replace Fastmail?
Fastmail works, but your data lives in someone else's account, the price can change at any time, and features can disappear. An open-source app you run yourself is yours: you choose where it runs, who can see the data, and when to update.
Questions
What is the best free alternative to Fastmail?
Stalwart Mail Server is the closest open-source replacement for Fastmail in our list. Mailcow and Mail-in-a-Box are worth a look too, depending on what you need.
Can I self-host an alternative to Fastmail?
Yes. All 5 apps on this page are open source and can run on your own server, usually with Docker, or on a managed host that installs them for you.