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WildDuck vs Apache James: catalog facts
WildDuck	Apache James
Free Free open-source software that you host yourself.	Free Free and open source from the Apache Software Foundation.
Linux, Self-hosted	Self-hosted
Horizontal scaling with no single point of failure Full IMAP4rev1 support with many extensions	Supports modern JMAP alongside SMTP, IMAP and POP3 Mailet container for custom mail processing
Needs MongoDB, Redis and separate SMTP components Aimed at large deployments rather than small personal 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 October 1, 2026	Official website Full listing and sources Checked October 2, 2026

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