Troubleshoot one specific message before changing an entire mailbox configuration. Record the sender, recipient, approximate sending time and time zone, subject and any delivery error. A message accepted by a receiving server can still be filtered after acceptance, so an apparent successful send does not prove that it reached the inbox.
Recommended workflow
- Test delivery between the affected mailbox and an external address, noting which direction fails.
- Compare the exact rejection with the mailbox quota, recipient spelling, DNS records and email authentication results.
- Check the available mail delivery logs and provide one recent example that support can trace, rather than a screenshot saying only that mail is missing.
For incoming problems, confirm that the domain uses the intended MX records and that the mailbox exists with available storage. Check spam folders, forwarding rules and filters. For outgoing problems, distinguish a connection or authentication error from a rejection returned by the destination server.
In a cPanel environment, Track Delivery can provide useful delivery events when the hosting provider enables that feature. Include the relevant result or message identifier in your support ticket. Preserve the full bounce text, but remove unrelated personal content. Avoid repeatedly resending large batches while a rejection is under investigation, because this adds noise and may worsen sending reputation.
