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Stalwart vs Mailu: catalog facts
Stalwart	Mailu
Free Free and open source, self-hosted.	Free Free and open source.
Linux, Self-hosted	Linux, Self-hosted
Modern JMAP support alongside traditional IMAP and SMTP protocols Rust implementation aims for security and performance	Webmail and admin interface included Per-domain delegation and quotas
Requires self-hosting and server administration knowledge Newer project with a smaller ecosystem than long-established mail servers	Requires Docker Releases are infrequent
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 September 24, 2026

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