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Stalwart vs Postal: catalog facts
Stalwart	Postal
Free Free and open source, self-hosted.	Free Free and open source to run on your own server.
Linux, Self-hosted	Self-hosted
Modern JMAP support alongside traditional IMAP and SMTP protocols Rust implementation aims for security and performance	Self-hosted alternative to hosted transactional email services Handles both sending and receiving mail
Requires self-hosting and server administration knowledge Newer project with a smaller ecosystem than long-established mail servers	Requires running and maintaining your own mail server Deliverability depends on your own server reputation and setup
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.