Emailing into Office 365 Groups triggers a NDR when emailing from internal sender
How to prevent a NDR when emailing into Opensense Groups
Option 1. Allow External Senders- This option will resolve the issue but is understandably not super desirable.
Option 2. Create an Exclusion Rule for Internal Senders emailing to Office 365 Groups. Follow these steps to prevent NDR from occurring. Keep in mind, that this will prevent signatures from being processed on these particular messages.
This rule will prevent the Opensense rule from applying to emails sent from internal senders to Office 365 groups, thereby eliminating the NDR issue.