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Cyrus IMAP vs Apache James: catalog facts
Cyrus IMAP	Apache James
Free Free and open source.	Free Free and open source from the Apache Software Foundation.
Linux, Self-hosted	Self-hosted
Mail, calendars and contacts in one server JMAP support alongside IMAP	Supports modern JMAP alongside SMTP, IMAP and POP3 Mailet container for custom mail processing
Complex to configure compared with all-in-one servers No bundled webmail	Requires a Java runtime and some server administration knowledge Distributed setups depend on extra services such as Cassandra
Self-hosted	Self-hosted
Open source	Open source
License not stated	License: Apache-2.0
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 October 2, 2026

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