Problem
Your email processed by the Signature Injection Service for Office 365 could not be delivered and you have received a non-delivery report from the Signature Injection Service or Microsoft 365.
Reason
The cause for the delivery problem is identified by an NDR code and description.
Normally the delivery problem will be due to user error such as a special mistake in an email address.
However, certain problems are specific to the transfer of email between Microsoft 365 and the Signature Injection Service. This article describes these particular problems and solutions.
Solution
Specific errors and solutions
Articles documenting specific errors and solutions:
- Non-delivery report 550 5.1.8 Access denied, bad outbound sender
- Non-delivery report 550 5.4.1 Recipient address rejected: Access denied
Configuration issues
Errors that only occur in relation to configuration issues:
- 550 5.7.64 Relay Access Denied ATTR36
- 451 4.4.5 Address domain different from previous accepted address. All recipients must be on the same domain ATTR46
- 451 4.4.62 Mail sent to the wrong Office 365 region. ATTR35
If receive a non-delivery report containing any of the above errors the potential reasons are:
- Signature Injection Service inbound and/or outbound connector are incorrectly configured in your Microsoft 365 tenant
Steps to resolve these problems will be added to this article. In the meantime, please contact support for assistance resolving the problem.