When email is sent to your inbound mailbox in Postmark and fails, you will receive an Inbound Error message. The Inbound Error message is shown when Postmark could not process the email that you have sent, or it could not deliver the JSON result to your web hook url.
This can happen due variety of reasons, but the most common ones are that destination URL for email processed is not set or that the URL is wrong or unreachable.
For more details about the issue, you can click on the message in the activity page for inbound emails. You would see a page with details about the email sent to inbound mailbox.
If you click on the “Inbound Error” link, you will see detailed information about why the email was not processed.
These error messages should help you troubleshoot issues on your own. If you need more information about why the mail was not processed by Postmark, please contact us and we will help you diagnose the issue.