What is Mox used for?

Mox is a modern, full-featured open-source mail server for low-maintenance self-hosted email, with SMTP, IMAP, webmail and spam filtering. It is a good fit for running mail for your own domain and replacing a hosted email provider with self-hosting.

Yes. Mox is open source under the MIT licence. Its source code is on GitHub at mjl-/mox and is written mainly in Go.

Yes. Mox is open source, so the software itself is free to use.

Yes. Mox can be self-hosted on your own server or infrastructure; there is no official hosted version.

What is Mox an alternative to?

Mox is an open-source alternative to Gmail, Fastmail, Zoho Mail and Proton Mail. Other open-source alternatives to Gmail include Mail-in-a-Box, Mailu and docker-mailserver.

Is Mox actively maintained?

Yes. The most recent commit to Mox was on 13 September 2026, and the latest release is v0.0.17, published on 19 August 2026. The project has 5.9k stars on GitHub.

Mox: open-source alternative to Gmail, Fastmail, Zoho Mail

About Mox

Mox is a mail server for people who want to run email for their own domains with little ongoing effort. It aims to be quick to start and to maintain, and it bundles the pieces of an email stack in one program.

Features include SMTP for receiving, submitting and delivering mail, IMAP4 for client access, and webmail in the browser. Authentication covers SPF, DKIM and DMARC, including DMARC aggregate reports. Spam handling is based on per-user reputation tracking and Bayesian filtering, and senders with low reputation can be slowed down, similar to greylisting. It supports internationalized email, automatic TLS via ACME for Let's Encrypt, DANE and MTA-STS with TLSRPT reporting, and account autodiscovery. A web admin interface helps set up domains, accounts and aliases and shows the DNS records to create.

Mox is written in Go and licensed under MIT. It is self-hosted software, and the project website provides details and a quickstart.

Key features

SMTP, IMAP4 and built-in webmail
SPF, DKIM and DMARC authentication
Per-user Bayesian spam filtering
Reputation tracking for senders
Automatic TLS with ACME
DANE and MTA-STS support
Web admin interface for domains and accounts

Good fit for

→Running mail for your own domain
→Replacing a hosted email provider with self-hosting

Built with: Go
Tags: mail-server; email; smtp; imap; webmail; spam-filtering; go; self-hosted

Mox: questions and answers

What is Mox used for?: Mox is a modern, full-featured open-source mail server for low-maintenance self-hosted email, with SMTP, IMAP, webmail and spam filtering. It is a good fit for running mail for your own domain and replacing a hosted email provider with self-hosting.
Is Mox open source?: Yes. Mox is open source under the MIT licence. Its source code is on GitHub at mjl-/mox and is written mainly in Go.
Is Mox free?: Yes. Mox is open source, so the software itself is free to use.
Can I self-host Mox?: Yes. Mox can be self-hosted on your own server or infrastructure; there is no official hosted version.
What is Mox an alternative to?: Mox is an open-source alternative to Gmail, Fastmail, Zoho Mail and Proton Mail. Other open-source alternatives to Gmail include Mail-in-a-Box, Mailu and docker-mailserver.
Is Mox actively maintained?: Yes. The most recent commit to Mox was on 13 September 2026, and the latest release is v0.0.17, published on 19 August 2026. The project has 5.9k stars on GitHub.