Courier Mail Server vs Citadel
A side-by-side comparison of two self-hosted apps from related categories — licensing, setup difficulty, resource needs, and what each one replaces.
Not the right match-up?
Courier Mail Server
Integrated mail server with IMAP, POP, and webmail
VS
Citadel
All-in-one groupware, mail and collaboration server
| Feature | Courier Mail Server | Citadel |
|---|---|---|
| Category | Mail Servers | Groupware |
| License | GPL-3.0 | GPL-3.0 |
| Language | C | C |
| Setup difficulty | Hard | Medium |
| Min. RAM | 512 MB | 512 MB |
| Deployment | bare-metal, source | bare-metal, source |
| GitHub stars | ★ 13 | ★ 100 |
| First released | 2000 | 1987 |
| Replaces | Microsoft Exchange | Microsoft Exchange, Microsoft 365 |
Why pick each one
Choose Courier Mail Server if…
- Released under the GPL-3.0 license
- Written in C
- Lightweight — runs in 512 MB RAM
Frequently asked questions
Is Courier Mail Server or Citadel better?
Citadel is the stronger all-round pick: it has both the larger community and the simpler medium setup. Consider Courier Mail Server if its specific feature set fits your needs better.
Are Courier Mail Server and Citadel free and open-source?
Yes. Courier Mail Server is licensed under GPL-3.0 and Citadel under GPL-3.0. Both can be self-hosted at no software cost.
Can I run Courier Mail Server and Citadel with Docker?
Courier Mail Server: check the project docs for container support. Citadel: check the project docs for container support.