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Zimbra vs SOGo: catalog facts
Zimbra	SOGo
Paid Sold in several editions under Zimbra's license terms; see the edition comparison.	Free Free and open source; paid premium support is offered separately.
Web, Self-hosted	Web, Self-hosted
Mail, calendar and contacts in one web client Can be run on your own servers	Webmail, calendars and contacts in one self-hosted server CalDAV, CardDAV and ActiveSync support for native and mobile clients
Aimed at organisations rather than individuals Running a mail server takes administration effort	Needs existing mail and directory servers to integrate with Outlook support depends on a separate CalDAV synchronizer
Self-hosted, Hosted service	Self-hosted
Closed source	Open source
License not stated	License: GPL-2.0-or-later / LGPL-2.0-or-later
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 September 23, 2026

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