Troubleshoot Common Zimbra Email Attachment Problems

  

Mark Regan
Published: February 19th, 2026 • 4 Min Read

In this guide we will share with you the best way to identify and fix Zimbra email problems. It also shows how to check server status, understand common errors, fix login and sending issues, resolve server-side failures, and help prevent common future issues. We will share the best methods to easily troubleshoot and restore your Zimbra email functionality.

As Zimbra Desktop is discontinued and no longer supported and no longer actively supported having reached its end of technical guidance around 2019. While older versions might still exist, it no longer receives updates, bug fixes, or security patches leading to performance issues and compatibility issues.

First Checks to Identify Zimbra Email Problems

Before applying any solution, first know the actual issue happening with your Zimbra Collaboration.

• Start by checking the main Zimbra services are running.
• Run command zmcontrol status to know all core services are active.
• If any service shows stopped the problem is likely on the server side.
• Next check the log files to know the actual issue.
• The primary log file is located at /var/log/zimbra.log and additional service logs can be found in /opt/zimbra/log.
• These logs show connection errors, authentication issues or service problems.
• Finally confirm whether the issue affects only you or all users.
• Try accessing emails from another browser, device or network.
• If anyone is affected, it’s likely a server issue. If only one user is affected the problem is in account settings, browser data or local configurations.

Common Zimbra Web Client Problems(For End Users)

• Clear browser cache and cookies to remove temp data.
• Switch between the Standard and Ajax versions of the Zimbra web client to see if one works better.
• Use supported browsers like Chrome or Firefox for optimal performance.
• Disable unnecessary Zimlets that could interfere with sending or receiving messages or slow down the client.
• Restart your browser or refresh the session to apply changes or fix temporary glitches.
• Check mailbox or briefcase storage limits if Zimbra email attachments are a problem.

Common Zimbra Server Problems(For Administrator)

• Fix MTA/Email Sending issues: verify permission using zmfixperms command.
• Ensure no other service is using port 25 (e.g., Sendmail).
• Resolve 502 Bad Gateway/ Proxy Errors: zmproxyctl restart.
• Check server memory or CPU usage to know the available space.
• LDAP Connection refused: Check SSL/TLS certificate is valid or expired.
• Verify LDAP service status and certificates if SSL is valid.
• Verify DNS and MX Records: dig mx yourdomain.com.

When is Zimbra Server Too Old?

Older Zimbra versions including, Zimbra Collaboration Suite 8.x can lead to frequent errors and ongoing maintenance issues due to the fact that, now they no longer receive software updates, or security patches. It is crucial to understand that using any outdated software comes with high hidden costs and poses greater security risks for your organization.

If you are facing issues and downtime regularly then it may be time to look for a reliable solution like Zimbra to Office 365 or Google Workspace can reduce maintenance, improve email reliability and provide ongoing security updates and also compare Zimbra vs Microsoft 365 to know the actual benefits of migration.

Conclusion

In this tutorial, we have explained all key techniques to fix Zimbra email problems. If your Zimbra server becomes too old or thinking of migrating then you can use Quick migration to maintain mailbox data without losing any information.