Mox review 2026: see how this Go-based, all-in-one open-source mail server handles SMTP, IMAP, webmail, spam filtering, and self-hosted email setup.
Mox is an open-source mail server designed to make self-hosted email realistic for individuals and small teams by collapsing the traditionally fragmented mail server stack into a single binary. Where a typical self-hosted setup requires separately configuring an SMTP daemon, an IMAP daemon, spam filtering, and DKIM signing, Mox implements all of these in one Go program.
Created by developer Mechiel Lukkien with work starting around 2021 and supported by grants from the NLnet Foundation's NGI Zero programs, Mox is positioned as a modern alternative to legacy mail server software, prioritizing security defaults and low operational overhead.
Mox handles the full email lifecycle: SMTP for receiving, submitting, and relaying mail, IMAP4rev2 for client access, and a built-in webmail client for reading and composing messages directly in the browser. It implements SPF, DKIM, and DMARC authentication along with DMARC aggregate reporting, plus MTA-STS, DANE, and TLSRPT for more secure, verifiable delivery.
Spam defenses include per-account reputation tracking, Bayesian filtering that learns from how users classify Junk and Non-Junk mail, and connection slowdowns for first-time senders. Operators get a web-based admin interface, Prometheus metrics, structured logging, and automatic TLS certificate issuance via ACME.
Mox is free, open-source software licensed under the MIT license, with no commercial tiers or subscription costs. Anyone can download the binary and self-host it on their own server.
Development is funded through public grants, primarily from the NLnet Foundation's NGI Zero programs and related European Commission Next Generation Internet initiatives, rather than through product sales.
Yes, Mox is free, open-source software released under the MIT license with no paid tiers.
Mox was created by developer Mechiel Lukkien, with development supported by grants from the NLnet Foundation's NGI Zero programs.
Mox implements SMTP, IMAP4rev2, SPF, DKIM, DMARC, MTA-STS, DANE, TLSRPT, and automatic TLS via ACME, along with a built-in webmail interface.
Yes, Mox ships with a built-in browser-based webmail client for reading and sending email without needing a separate mail app.
Postfix and Dovecot are separate SMTP and IMAP daemons that must be configured and connected together, while Mox combines equivalent SMTP, IMAP, and webmail functionality into a single Go binary.
Mox is written in Go, chosen for its memory safety and suitability for building a secure, low-maintenance server application.