SHSelfHostIndex

Cyrus IMAP vs WildDuck

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 WI WildDuck Scalable IMAP and POP3 mail server with REST API
FeatureCyrus IMAPWildDuck
Deploy effortRead-the-docs projectUnder-an-hour setup
Health score80 · Excellent86 · Excellent
CategoryMail ServersMail Servers
LicenseBSD-3-ClauseEUPL-1.2
LanguageCJavaScript
Setup difficultyHardHard
Min. RAM1,024 MB1,024 MB
Deploymentbare-metal, sourcedocker, bare-metal
GitHub stars★ 648★ 2,108
First released19942017
ReplacesMicrosoft ExchangeMicrosoft Exchange, Gmail

What are Cyrus IMAP and WildDuck?

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

WildDuck

WildDuck is a modern, scalable mail server providing IMAP, POP3, and a full REST API for managing mailboxes. It stores messages in MongoDB and is designed for clustered, highly available deployments.

  • IMAP and POP3
  • Full REST API
  • MongoDB storage
  • Designed for scale

Read the full WildDuck guide →

Cyrus IMAP vs WildDuck: key differences

Cyrus IMAP is written in C, while WildDuck is built with JavaScript. Licensing differs — BSD-3-Clause for Cyrus IMAP versus EUPL-1.2 for WildDuck. Cyrus IMAP is the more established project (first released 1994), while WildDuck arrived in 2017. WildDuck has the considerably larger community, at 2,108 GitHub stars versus 648. WildDuck lists first-class Docker deployment; Cyrus IMAP does not.

Why pick each one

Choose Cyrus IMAP if…

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

Choose WildDuck if…

  • API-driven management
  • Horizontally scalable

Watch out for

  • Requires MongoDB
  • Complex to operate
WildDuck details

Frequently asked questions

Is Cyrus IMAP or WildDuck better?

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

Are Cyrus IMAP and WildDuck free and open-source?

Yes. Cyrus IMAP is licensed under BSD-3-Clause and WildDuck under EUPL-1.2. Both can be self-hosted at no software cost.

Can I run Cyrus IMAP and WildDuck with Docker?

Cyrus IMAP: check the project docs for container support. WildDuck: yes.

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