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Cyrus IMAP vs Stalwart: catalog facts
Cyrus IMAP	Stalwart
Free Free and open source.	Free Free and open source, self-hosted.
Linux, Self-hosted	Linux, Self-hosted
Mail, calendars and contacts in one server JMAP support alongside IMAP	Modern JMAP support alongside traditional IMAP and SMTP protocols Rust implementation aims for security and performance
Complex to configure compared with all-in-one servers No bundled webmail	Requires self-hosting and server administration knowledge Newer project with a smaller ecosystem than long-established mail servers
Self-hosted	Self-hosted
Open source	Open source
License not stated	License not stated
No account needed	Not stated if an account is 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 22, 2026

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