11 Best Free & Open-Source Self-Hosted Email Servers (2025 Edition)

11 Best Free & Open-Source Self-Hosted Email Servers (2025 Edition)

11 Best Free & Open-Source Self-Hosted Email Servers (2025 Edition)

Want full control over your email? Tired of relying on Gmail, Outlook, or other third-party providers?

Self-hosting your own email server gives you total privacy, custom domains, and the freedom to run things your way — all while saving money (especially with open-source tools).

As someone with 5 years of SEO and digital infrastructure experience, I’ve helped individuals, developers, and small businesses set up secure, reliable email servers from scratch. In this guide, I’ll walk you through 11 free and open-source email servers you can host yourself — without the jargon, and with honest pros and cons.

Let’s dive in! 🖥️📬

1. Mailcow: Dockerized

✅ Best for: All-in-one email hosting with modern features

Mailcow is one of the most popular open-source email server stacks. It runs in Docker, making setup and updates easier for developers and sysadmins.

Key Features:

• Built-in spam filtering (Rspamd)

• Webmail (SOGo), DKIM, SPF, DMARC

• 2FA, mobile sync, easy admin UI

Pros:

• Clean dashboard

• Active community

• Fully featured, even for teams

Cons:

• Docker knowledge required

• Higher system requirements

2. iRedMail

✅ Best for: Quick, full-featured setup

iRedMail is a one-click email server solution for Linux that comes with Postfix, Dovecot, SpamAssassin, ClamAV, and Roundcube.

Key Features:

• Secure by default (SSL, DKIM, DMARC)

• LDAP or MySQL backends

• Roundcube webmail

Pros:

• Straightforward installer

• Excellent documentation

Cons:

• Free version is command-line only

• No built-in admin panel unless you pay

3. Mailu

✅ Best for: Lightweight, modular Docker setup

Mailu is a simple yet powerful mail server built using Docker Compose. It includes all the essentials like Postfix, Dovecot, Rspamd, and admin UI.

Key Features:

• Small and lightweight

• Secure defaults

• Webmail and admin panel included

Pros:

• Easy to deploy and scale

• No root access needed inside containers

Cons:

• Advanced features need manual config

• Community smaller than Mailcow

4. Modoboa

✅ Best for: Admin-friendly UI with optional paid support

Modoboa is a Python-based email server with a very intuitive web interface. It’s great for those who want GUI control and useful analytics.

Key Features:

• User/domain management UI

• Amavis + ClamAV integration

• Webmail, calendar, and contacts

Pros:

• Beautiful admin dashboard

• Plugin system

• Mobile-friendly interface

Cons:

• More complex than iRedMail

• Resource-heavy on large installs

5. Poste.io

✅ Best for: Quick Docker deployment with a sleek UI

Poste.io is a self-contained mail server that runs in Docker with a modern web UI and built-in security features.

Key Features:

• Easy web-based setup

• DKIM, SPF, DMARC, antivirus

• ActiveSync support (paid version)

Pros:

• One of the easiest setups

• Great UX for managing domains & users

Cons:

• Some features are paid-only

• Less community documentation than others

6. Citadel

✅ Best for: Full groupware + email stack

Citadel is more than just an email server — it’s a complete collaboration suite (mail, calendar, notes, etc.) with a retro but powerful interface.

Key Features:

• Email, calendar, contacts, tasks

• Real-time chat server included

• Multiple access protocols (SMTP, IMAP, XMPP)

Pros:

• Lightweight and stable

• Includes webmail and groupware tools

Cons:

• Outdated UI

• Not ideal for modern branding

7. Haraka

✅ Best for: Developers needing a fast SMTP server

Haraka is a Node.js-based SMTP server designed for speed and flexibility. It’s especially useful if you're building custom email tools or need a lightweight mail relay.

Key Features:

• Plugin-based architecture

• Extremely fast SMTP performance

• Easily extendable with JavaScript

Pros:

• Great for devs

• Lightweight and fast

Cons:

• No webmail or inbox support

• SMTP only — not a full server stack

8. Dovecot + Postfix (Manual Setup)

✅ Best for: Full control and customization

Want to build your email server from scratch? Combine Postfix (for sending) and Dovecot (for receiving/IMAP) with optional tools like SpamAssassin and ClamAV.

Key Features:

• Fully modular

• Ideal for power users

• Compatible with Roundcube or RainLoop

Pros:

• Total flexibility

• Great for learning how email servers work

Cons:

• Manual setup is complex

• Requires ongoing maintenance

9. Mail-in-a-Box

✅ Best for: Beginners who want a plug-and-play setup

Mail-in-a-Box turns your cloud server (like DigitalOcean or Linode) into a working email server in under an hour.

Key Features:

• Automated installation

• DNS, SSL, spam filtering handled

• Roundcube webmail included

Pros:

• Extremely beginner-friendly

• Self-maintaining (auto-updates, backups)

Cons:

• Limited flexibility

• Not ideal for complex configs

10. WildDuck Mail Server

✅ Best for: Modern API-first email server

WildDuck is a modern, scalable mail server written in Node.js and built with MongoDB. It’s designed for developers and large deployments.

Key Features:

• Fully API-driven

• IMAP, SMTP, JMAP support

• High performance, scalable

Pros:

• Works well with modern frontends

• Great for advanced developers

Cons:

• Requires technical knowledge

• Not beginner-friendly

11. Maddy

✅ Best for: Single binary, minimal dependencies

Maddy (aka Maddy Mail Server) is a compact, all-in-one email server written in Go. It’s relatively new but aims to make mail hosting easier.

Key Features:

• SMTP, IMAP, LMTP in one binary

• TLS, DKIM, SPF support

• SQLite or Redis backend

Pros:

• Simple deployment

• Actively maintained

Cons:

• Still maturing

• Not as feature-rich as Mailcow or iRedMail

✅ Final Thoughts: Which Self-Hosted Mail Server Should You Choose?

Here’s a quick recommendation based on your experience level and needs:

🔒 Pro Tip: Always set up proper DNS (SPF, DKIM, DMARC) and use SSL (Let's Encrypt) to avoid email deliverability issues or being flagged as spam.