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WildDuck vs Zimbra: catalog facts
WildDuck	Zimbra
Free Free open-source software that you host yourself.	Paid Sold in several editions under Zimbra's license terms; see the edition comparison.
Linux, Self-hosted	Web, Self-hosted
Horizontal scaling with no single point of failure Full IMAP4rev1 support with many extensions	Mail, calendar and contacts in one web client Can be run on your own servers
Needs MongoDB, Redis and separate SMTP components Aimed at large deployments rather than small personal servers	Aimed at organisations rather than individuals Running a mail server takes administration effort
Self-hosted	Self-hosted, Hosted service
Open source	Closed source
License not stated	License not stated
Not stated if an account is needed	Not stated if an account is 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 1, 2026

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