Exim vs mailcow
A side-by-side comparison of two self-hosted mail servers options — licensing, setup difficulty, resource needs, and what each one replaces.
mailcow
Dockerized full-stack mail server suite
| Feature | Exim | mailcow |
|---|---|---|
| Deploy effort | Read-the-docs project | Under-an-hour setup |
| Health score | 15 · At risk | 94 · Excellent |
| Status | Archived | Actively maintained |
| Category | Mail Servers | Mail Servers |
| License | GPL-2.0 | GPL-3.0 |
| Language | C | JavaScript |
| Setup difficulty | Hard | Medium |
| Min. RAM | 64 MB | 6,144 MB |
| Deployment | bare-metal, source | docker |
| GitHub stars | ★ 785 | ★ 13,498 |
| First released | 1995 | 2016 |
| Replaces | Microsoft Exchange | Microsoft Exchange, Google Workspace |
What are Exim and mailcow?
Exim
Exim is a highly configurable mail transfer agent used to route and deliver email on Unix systems. It powers a large share of the internet's mail servers and supports extensive policy and ACL controls.
- Powerful routing rules
- ACL-based policy
- Wide platform support
- Mature codebase
mailcow
mailcow is a complete, Docker-based mail server solution that bundles Postfix, Dovecot, Rspamd, SOGo, and a modern web UI. It makes running a full-featured mail server with antispam and webmail straightforward.
- Complete Docker mail stack
- Rspamd antispam built in
- SOGo webmail and ActiveSync
- Modern management UI with API
Exim vs mailcow: key differences
The biggest difference is maintenance: Exim's repository is archived and no longer developed, while mailcow is actively maintained. Exim is written in C, while mailcow is built with JavaScript. Licensing differs — GPL-2.0 for Exim versus GPL-3.0 for mailcow. Exim is the lighter option, starting around 64 MB of RAM against 6,144 MB for mailcow. Exim is the more established project (first released 1995), while mailcow arrived in 2016. Mailcow has the considerably larger community, at 13,498 GitHub stars versus 785. Mailcow lists first-class Docker deployment; Exim does not.
Why pick each one
Choose Exim if…
- Extremely flexible
- Proven at scale
Watch out for
- Complex configuration
- Easy to misconfigure
Choose mailcow if…
- All components preconfigured
- Active community
Watch out for
- Substantial RAM requirements
- Many containers to manage
Frequently asked questions
Is Exim or mailcow better?
mailcow is the stronger all-round pick: it has both the larger community and the simpler medium setup. Consider Exim if its specific feature set fits your needs better.
Are Exim and mailcow free and open-source?
Yes. Exim is licensed under GPL-2.0 and mailcow under GPL-3.0. Both can be self-hosted at no software cost.
Can I run Exim and mailcow with Docker?
Exim: check the project docs for container support. mailcow: yes.
Which is lighter on resources, Exim or mailcow?
Exim has the smaller minimum footprint at 64 MB of RAM, compared to about 6,144 MB for mailcow. Real-world usage depends on library size, user count, and enabled features.