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Stalwart vs Courier Mail Server: catalog facts
Stalwart	Courier Mail Server
Free Free and open source, self-hosted.	Free Free and open-source software.
Linux, Self-hosted	Linux, Self-hosted
Modern JMAP support alongside traditional IMAP and SMTP protocols Rust implementation aims for security and performance	SMTP, IMAP, POP3, webmail and mailing lists in one package Components can be switched on or off individually
Requires self-hosting and server administration knowledge Newer project with a smaller ecosystem than long-established mail servers	Built from source on POSIX systems, with no Windows support Calendaring in the webmail is basic
Self-hosted	Self-hosted
Open source	Open source
License not stated	License not stated
Not stated if an account is needed	No account needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked September 22, 2026	Official website Full listing and sources Checked October 2, 2026

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