Mox is a modern full-featured open source secure mail server for low-maintenance self-hosted email.
Excellent quality (open source) mail server software exists, but getting a working setup typically requires you configure half a dozen services (SMTP, IMAP, SPF/DKIM/DMARC, spam filtering), which are often written in C (where small bugs often have large consequences). That seems to lead to individuals no longer running their own mail servers, instead switching to one of the few centralized email providers. Email with SMTP is a long-time decentralized messaging protocol. To keep it decentralized, people need to run their own mail server. Mox aims to make that easy.
This is free and open source software.
Features include:
- Quick and easy to start/maintain mail server, for your own domain(s). Get a machine, download the mox binary, run the quickstart, add the printed DNS records, and you’ve got a working modern mail server.
- SMTP (with extensions) for receiving, submitting and delivering email.
- IMAP4 (with extensions) for giving email clients access to email.
- Webmail for reading/sending email from the browser.
- SPF/DKIM/DMARC for authenticating messages/delivery, also DMARC aggregate reports.
- Reputation tracking, learning (per user) host-, domain- and sender address-based reputation from (Non-)Junk email classification.
- Bayesian spam filtering that learns (per user) from (Non-)Junk email.
- Slowing down senders with no/low reputation or questionable email content (similar to greylisting). Rejected emails are stored in a mailbox called Rejects for a short period, helping with misclassified legitimate synchronous signup/login/transactional emails.
- Internationalized email, with unicode in email address usernames (“localparts”), and in domain names (IDNA).
- Automatic TLS with ACME, for use with Let’s Encrypt and other CA’s.
- DANE and MTA-STS for inbound and outbound delivery over SMTP with STARTTLS, including REQUIRETLS and with incoming/outgoing TLSRPT reporting.
- Web admin interface that helps you set up your domains, accounts and list aliases (instructions to create DNS records, configure SPF/DKIM/DMARC/TLSRPT/MTA-STS), for status information, and modifying the configuration file.
- Account autodiscovery (with SRV records, Microsoft-style, Thunderbird-style, and Apple device management profiles) for easy account setup (though client support is limited).
- Webserver with serving static files and forwarding requests (reverse proxy), so port 443 can also be used to serve websites.
- Simple HTTP/JSON API for sending transaction email and receiving delivery events and incoming messages (webapi and webhooks).
- Prometheus metrics and structured logging for operational insight.
- “mox localserve” subcommand for running mox locally for email-related testing/developing, including pedantic mode.
- Most non-server Go packages mox consists of are written to be reusable.
Website: www.xmox.nl
Support: GitHub Code Repository
Developer: Mechiel Lukkien
License: MIT License
mox is written in Go. Learn Go with our recommended free books and free tutorials.
| Popular series | |
|---|---|
 | The largest compilation of the best free and open source software in the universe. Each article is supplied with a legendary ratings chart helping you to make informed decisions. |
 | Hundreds of in-depth reviews offering our unbiased and expert opinion on software. We offer helpful and impartial information. |
 | Replace proprietary software with open source alternatives: Google, Microsoft, Apple, Adobe, IBM, Autodesk, Oracle, Atlassian, Corel, Cisco, Intuit, and SAS. |
 | Awesome Free Linux Games Tools showcases a series of tools that making gaming on Linux a more pleasurable experience. This is a new series. |
 | Machine Learning explores practical applications of machine learning and deep learning from a Linux perspective. We've written reviews of more than 40 self-hosted apps. All are free and open source. |
 | New to Linux? Read our Linux for Starters series. We start right at the basics and teach you everything you need to know to get started with Linux. |
 | Alternatives to popular CLI tools showcases essential tools that are modern replacements for core Linux utilities. |
 | Essential Linux system tools focuses on small, indispensable utilities, useful for system administrators as well as regular users. |
 | Linux utilities to maximise your productivity. Small, indispensable tools, useful for anyone running a Linux machine. |
 | Surveys popular streaming services from a Linux perspective: Amazon Music Unlimited, Myuzi, Spotify, Deezer, Tidal. |
 | Saving Money with Linux looks at how you can reduce your energy bills running Linux. |
 | Home computers became commonplace in the 1980s. Emulate home computers including the Commodore 64, Amiga, Atari ST, ZX81, Amstrad CPC, and ZX Spectrum. |
 | Now and Then examines how promising open source software fared over the years. It can be a bumpy ride. |
 | Linux at Home looks at a range of home activities where Linux can play its part, making the most of our time at home, keeping active and engaged. |
 | Linux Candy reveals the lighter side of Linux. Have some fun and escape from the daily drudgery. |
 | Getting Started with Docker helps you master Docker, a set of platform as a service products that delivers software in packages called containers. |
 | Best Free Android Apps. We showcase free Android apps that are definitely worth downloading. There's a strict eligibility criteria for inclusion in this series. |
 | These best free books accelerate your learning of every programming language. Learn a new language today! |
 | These free tutorials offer the perfect tonic to our free programming books series. |
 | Linux Around The World showcases usergroups that are relevant to Linux enthusiasts. Great ways to meet up with fellow enthusiasts. |
 | Stars and Stripes is an occasional series looking at the impact of Linux in the USA. |