Troubleshooting Inbound Email Delivery Issues

If you are experiencing problems where inbound emails are delayed, missing, or stuck in queue on your Email Security Gateway, follow the steps below.

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1. Check Message Log

• Log into the Email Security Gateway web interface.

• Go to Basic > Message Log.

• Search for the affected email addresses or domains.

• Review the “Action” and “Reason” columns for clues (e.g., deferred, blocked, queued).

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2. Verify DNS and MX Records

• Confirm that your domain’s MX records are correctly pointing to the appliance or cloud service.

• Use tools like nslookup, dig, or an online DNS checker.

• Ensure no typos or expired records exist.

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3. Check Appliance Health

• Navigate to Basic > Dashboard.

• Confirm that CPU, memory, and storage usage are within normal ranges.

• Verify that the appliance shows a green system status.

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4. Review Network and Firewall Settings

• Make sure the appliance can communicate on port 25 (SMTP).

• Verify that your firewall is not blocking or throttling connections.

• Confirm that your ISP is not filtering incoming SMTP traffic.

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5. Inspect Queue

• Go to Advanced > Queue in the Barracuda interface.

• If many emails are stuck in queue, note the error messages.

• A common issue may be a DNS resolution failure or upstream delivery block.

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6. Restart Services

• If issues persist, restart the mail processing service or reboot the appliance from Advanced > Troubleshooting.

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7. When to Contact Support

If emails remain undelivered after completing these steps, please gather the following before opening a support case:

• Appliance model and firmware version

• Serial number

• Sample senders and recipients affected

• Error codes or log entries observed