Horde vs Zimbra (2026): which should you pick?

Horde

• Admins who want a free groupware suite with webmail on their own server
• Organizations that need shared calendars and address books without licensing fees
• Developers who want to reuse Horde's PHP libraries

Zimbra

• Companies and schools that need to keep email on servers they control
• Hosting providers offering white-labeled email to customers
• Teams moving off Microsoft Exchange who want Outlook compatibility

Horde

• You install and maintain it yourself; it is a client and groupware layer that needs your own mail server.
• Support is community-based; the project points to B1 Systems for paid hosting and support.
• The project blog describes recent releases (Horde 6, IMP 7) with rough edges and a security fix shortly after launch.
• It is community-maintained with no vendor behind it, so there is no service-level guarantee.

Zimbra

• Pricing is not published; Zimbra is licensed, and renewals go through an account manager.
• The FAQ calls the Open Source Edition end of life, with no updates or support.
• Features such as backup and restore, Zimbra Office and large-scale mobile sync need the commercial license.
• Chat and real-time collaboration are protected in transit only, not end-to-end encrypted.

Horde

Webmail client

IMAP and POP3 mail with 3-pane and 3-column layouts, conversation view, filtering, searching and a WYSIWYG composer.

Message security

Encrypting and signing messages with S/MIME and PGP, plus quota support and shared IMAP folders.

Calendars, contacts and tasks

Shared calendars, address books, task lists and notepads, with unlimited resources per user.

Sync with other clients

CalDAV, CardDAV and ActiveSync support, plus responsive, basic and mobile interfaces.

Wider app suite

Applications for files, bookmarks, time tracking and more can be added, and the PHP libraries underneath are reusable.

Translations

The groupware pages say it is translated into 41 languages, including right-to-left scripts.

Zimbra

Mail, calendar and contacts

A web client with advanced and attachment search, personal and global address lists, group and resource scheduling, and tasks.

Two editions

Zimbra Daffodil (v10) needs a license, sold as Professional or Standard. Professional has additional features over Standard.

Desktop and mobile access

Zimbra Desktop for Windows, macOS and Linux, a Connector for Outlook on Windows, and ActiveSync on iOS and Android.

Standards-based clients

Works with IMAP, POP, CalDAV and CardDAV, so Thunderbird, Apple Mail and similar clients can connect.

Security and admin controls

Built-in anti-spam and antivirus, two-factor sign-in, LDAP or Active Directory, SAML sign-in and delegated administration.

Deployment options

Install on your own servers, run it in the cloud on AWS or OCI, or use a hosting partner, with multiple domains per install.

Horde

• Horde Groupware$0

  Free LGPL and GPL software you host yourself. Paid support comes from third-party sponsors such as B1 Systems.

Zimbra

Pricing could not be confirmed. See zimbra.com.