SHSelfHostIndex

Cyrus IMAP vs Exim

A side-by-side comparison of two self-hosted mail servers options — licensing, setup difficulty, resource needs, and what each one replaces.

Not the right match-up?
CY Cyrus IMAP Scalable IMAP and POP server for large deployments VS EX Exim Flexible and widely deployed mail transfer agent
FeatureCyrus IMAPExim
CategoryMail ServersMail Servers
LicenseBSD-3-ClauseGPL-2.0
LanguageCC
Setup difficultyHardHard
Min. RAM1,024 MB64 MB
Deploymentbare-metal, sourcebare-metal, source
GitHub stars★ 641★ 786
First released19941995
ReplacesMicrosoft ExchangeMicrosoft Exchange

Why pick each one

Choose Cyrus IMAP if…

  • Released under the BSD-3-Clause license
  • Written in C
Cyrus IMAP details

Choose Exim if…

  • Extremely flexible
  • Proven at scale
Exim details

Frequently asked questions

Is Cyrus IMAP or Exim better?

Neither is universally better. Exim has the larger community; both share a hard setup difficulty, so the decision comes down to features and licensing.

Are Cyrus IMAP and Exim free and open-source?

Yes. Cyrus IMAP is licensed under BSD-3-Clause and Exim under GPL-2.0. Both can be self-hosted at no software cost.

Can I run Cyrus IMAP and Exim with Docker?

Cyrus IMAP: check the project docs for container support. Exim: check the project docs for container support.

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