Frequently Asked Questions
(FAQ)

Zimbra is a secure, standards-based enterprise email and collaboration suite by Synacor. It delivers robust email, calendar, contacts, tasks, and file-sharing functionality — designed for businesses, educational institutions, and service providers to boost productivity and enable seamless cross-organization interaction.

Web Access
Zimbra’s HTML5-based web client runs on any modern browser — Google Chrome, Mozilla Firefox, Microsoft Edge, and Apple Safari—across Windows, macOS, Linux, and Chrome OS.

Desktop Clients

• Zimbra Desktop (Windows, macOS, Linux)
• Mozilla Thunderbird (with Lightning for calendar)
• Microsoft Outlook via the Zimbra Connector for Outlook
• Apple Mail, Windows Mail, IMAP/CalDAV/CardDAV-capable clients

Mobile Devices

• Zimbra Mobile (ActiveSync) on iOS and Android
• Third-party ActiveSync clients (e.g., Outlook Mobile, Nine, Airmail)
• Native iOS/Android mail, calendar, and contacts apps via IMAP, CalDAV, and CardDAV

Zimbra’s core server and web client are released under the GPLv2 license, with full source code published on GitHub. However, Synacor distributes pre-built binaries and a set of advanced features such as Hierarchical storage management, Advanced Chat, Robust backup/recovery tool, Zimbra Office & Document Editing and large-scale mobile sync — in its commercially licensed community version.

• S/MIME Encryption and Digital Signing

Zimbra’s native mail client and desktop/mobile connectors support S/MIME v3 certificates for full end-to-end encryption and digital signatures. Users import their personal certificates (X.509) into their mailbox to encrypt outgoing messages and verify incoming mail authenticity.

• TLS for Transport Security

All SMTP, IMAP, POP and HTTP(S) connections in Zimbra are encrypted in transit with TLS, protecting data between clients and servers (but this does not provide true end-to-end protection at rest).

• Limitations on Chat and Collaboration

Zimbra Chat and real-time collaboration features rely on TLS in transit but do not support end-to-end encryption of message content at the client level.

Data Encryption at Rest

• S/MIME certificate support for encrypting and digitally signing stored emails and attachments.

Data Encryption in Transit

• TLS-secured connections for SMTP(S), IMAP(S), POP(S), HTTP(S) web client, and ActiveSync.

Threat Protection

• Built-in anti-spam filtering engine
• Integrated antivirus scanning for inbound and outbound messages

Authentication and Access Control

• Integration with LDAP and Microsoft Active Directory for single sign-on
• SAML-based federated authentication (e.g., Okta, Azure AD)
• Two-factor authentication (TOTP apps, SMS, or hardware tokens)
• Device-level authentication binding and access controls
• Delegated administration with granular, role-based permissions

Auditing and Compliance

• Comprehensive audit logs capturing mailbox access, administrative actions, and configuration changes

Zimbra offers features and deployment options that enable organizations to meet GDPR requirements and support HIPAA-related safeguards. However, ultimate compliance responsibility rests with the organization acting as the data controller and processor. Zimbra provides the technical flexibility and control, however, the responsibility for proper configuration, policies, and operational practices rests with the organization.

• Hosted by BSP partners
• Cloud (AWS, OCI, private/hybrid)
• On-premises

Yes, Zimbra supports custom domain hosting and multi-tenant setup, each with independent configurations.

Yes, via Zimlets or APIs, Zimbra integrates with popular tools like Slack, Zoom, Google Drive, OneDrive, and Dropbox.

• Web Client: HTML5 interface in any modern browser (Chrome, Firefox, Edge, Safari) on Windows, macOS, or Linux
• Zimbra Desktop: Cross-platform app with offline mail, calendar, contacts, tasks, and document sync
• Outlook Integration: Zimbra Connector for Outlook (ZCO) for Windows; Exchange Web Services (EWS) for Outlook for Mac and Apple Mail
• Standard Clients: IMAP/POP3 for mail and SMTP for sending in any compatible email client

• Exchange ActiveSync (EAS)
  Push-sync email, calendar, contacts, and tasks with built-in clients on iOS and Android.
• Exchange Web Services (EWS) for macOS
  Configure Apple Mail, Calendar, and Contacts as Exchange accounts for tight desktop-to-server sync.
• Responsive Web & PWA
  Mobile-optimized HTML5 client that can be “installed” from the browser
• Third-Party EAS Apps
  Outlook Mobile, Nine, Airmail, etc.
• Standard Protocols
  IMAP/SMTP, CalDAV for calendars, CardDAV for contacts
• Zimbra Mobile (Zimlets & APIs)
  Extend mobile functionality with custom Zimlets or leverage REST APIs for MDM and specialized workflows.

Yes, all major email clients are supported via IMAP, POP, ActiveSync, and Exchange Web Services.

Uses SpamAssassin, ClamAV, DoS filters, grey-/blacklists, SPF, and throttling tools to prevent threats.

Yes, built-in features allow transparent archiving at the mailbox level with configurable retention policies.

Zimbra follows a predictable update schedule to balance stability and innovation:

• Regular security patches for critical vulnerabilities
• Periodic cumulative updates bundling bug fixes and minor enhancements
• Feature releases introducing new capabilities and user experience improvements
• Major version updates delivering significant platform advancements

You can stay informed about every release via:

• Zimbra Downloads page (official binaries and patch listings)
• Zimbra Community forums and announcement mailing lists
• Zimbra blog for product roadmaps and upcoming features
• Release Notes section on Zimbra’s documentation site

Zimbra OSE is an end-of-life version with no updates or support. With no updates, security fixes or feature upgrades, this poses security risks, compliance issues, and business disruption. Besides, Zimbra Network Edition offers additional advanced security features, ActiveSync/Mobile, HSM, Backup and Restore and Delegated Admin.

From small teams to multi-million user deployments — Zimbra scales efficiently at enterprise level.

Yes, custom branding, UI, 2FA, SSO, spam engines, and more can be tailored to meet organizational needs.

• Self-help: Wiki, blogs, forums
• BSP partners for local support and consulting
• Professional services for advanced deployments
• Standard & Professional support plans offering varying SLAs

• Submit a ticket via Support Portal, email, or phone
• Portal access includes ticket management and knowledge articles

Please refer to our SLA details here: https://www.zimbra.com/connect/support/sla-info/

Yes, contact your Account Manager or renewals@zimbra.com. Fees and policies vary depending on license type.