Cyrus IMAP 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 | Cyrus IMAP | mailcow |
|---|---|---|
| Deploy effort | Read-the-docs project | Under-an-hour setup |
| Health score | 80 · Excellent | 94 · Excellent |
| Category | Mail Servers | Mail Servers |
| License | BSD-3-Clause | GPL-3.0 |
| Language | C | JavaScript |
| Setup difficulty | Hard | Medium |
| Min. RAM | 1,024 MB | 6,144 MB |
| Deployment | bare-metal, source | docker |
| GitHub stars | ★ 648 | ★ 13,498 |
| First released | 1994 | 2016 |
| Replaces | Microsoft Exchange | Microsoft Exchange, Google Workspace |
What are Cyrus IMAP and mailcow?
Cyrus IMAP
Cyrus IMAP is an enterprise-grade mail server designed to scale to very large numbers of mailboxes, with its own optimized mail store. It supports IMAP, POP, JMAP, and server-side search.
- Scales to many mailboxes
- Optimized mail store
- JMAP and IMAP support
- Server-side search
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
Cyrus IMAP vs mailcow: key differences
Cyrus IMAP is written in C, while mailcow is built with JavaScript. Licensing differs — BSD-3-Clause for Cyrus IMAP versus GPL-3.0 for mailcow. Cyrus IMAP is the lighter option, starting around 1,024 MB of RAM against 6,144 MB for mailcow. Cyrus IMAP is the more established project (first released 1994), while mailcow arrived in 2016. Mailcow has the considerably larger community, at 13,498 GitHub stars versus 648. Mailcow lists first-class Docker deployment; Cyrus IMAP does not.
Why pick each one
Choose mailcow if…
- All components preconfigured
- Active community
Watch out for
- Substantial RAM requirements
- Many containers to manage
Frequently asked questions
Is Cyrus IMAP or mailcow better?
mailcow is the stronger all-round pick: it has both the larger community and the simpler medium setup. Consider Cyrus IMAP if its specific feature set fits your needs better.
Are Cyrus IMAP and mailcow free and open-source?
Yes. Cyrus IMAP is licensed under BSD-3-Clause and mailcow under GPL-3.0. Both can be self-hosted at no software cost.
Can I run Cyrus IMAP and mailcow with Docker?
Cyrus IMAP: check the project docs for container support. mailcow: yes.
Which is lighter on resources, Cyrus IMAP or mailcow?
Cyrus IMAP has the smaller minimum footprint at 1,024 MB of RAM, compared to about 6,144 MB for mailcow. Real-world usage depends on library size, user count, and enabled features.