I have created a more detailed example of how to do this here: https://bhr.62e.myftpupload.com/2018/09/14/fixing-office-365-anonymous-group-write-back-and-external-delivery/
Office 365 Groups are glorious creations. There are, however, some instances where they don’t work as you anticipate (or hope). One of those scenarios is when you are configured in hybrid coexistence with the following scenario:
- Office 365 Group Writeback is enabled (for configuring permissions, see this script)
- RequireSenderAuthenticationEnabled is set to False for an Office 365 group
- Your organization’s MX record is configured to point on-premises
In this scenario, external emails sent to Office 365 groups (via your organization’s MX record pointing on-premises) will be returned with one of our favorite NDRs:
“You do not have permission to send to this recipient.”… [ Continue reading ]