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Cyrus IMAP vs Baïkal: catalog facts
Cyrus IMAP	Baïkal
Free Free and open source.	Free Free and open source under the GPL v3.
Linux, Self-hosted	Self-hosted
Mail, calendars and contacts in one server JMAP support alongside IMAP	Runs on any basic PHP host Web interface for users, calendars and address books
Complex to configure compared with all-in-one servers No bundled webmail	No built-in calendar or contacts web client for end users Docker installation is only unofficial
Self-hosted	Self-hosted
Open source	Open source
License not stated	License: GPL-3.0
No account needed	No account needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked September 24, 2026	Official website Full listing and sources Checked September 24, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.