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Stalwart vs Apache James: catalog facts
Stalwart	Apache James
Free Free and open source, self-hosted.	Free Free and open source from the Apache Software Foundation.
Linux, Self-hosted	Self-hosted
Modern JMAP support alongside traditional IMAP and SMTP protocols Rust implementation aims for security and performance	Supports modern JMAP alongside SMTP, IMAP and POP3 Mailet container for custom mail processing
Requires self-hosting and server administration knowledge Newer project with a smaller ecosystem than long-established mail servers	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
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.