After a user’s mailbox is migrated to Microsoft Office 365, they receive meeting requests from an on-premises room mailbox of which the user is a delegate, as expected.
However, these meetings show on the user’s calendar directly as if they were added as an attendee by the organizer. Also, any attempt to accept or decline the request comes directly from the user, instead of from the resource mailbox.
This issue occurs if the following conditions are true:
- The resource delegate of the on-premises room mailbox is a distribution group that contains the cloud user.
- Transport Neutral Encapsulation Format (TNEF) is not explicitly enabled on the remote domain that’s used when the meeting requests are sent to the cloud mailbox.
To resolve this issue, use one of the following methods.
To resolve the issue at an organizational level (recommended), enable TNEF on the *.mail.onmicrosoft.com remote domain, depending on what is used as the target address for cloud users. To do this, run the following cmdlet:
Set-RemoteDomain <domain> - TNEFEnabled $true
To resolve the issue at a single-user level, remove the distribution group as the resource delegate for the room mailbox, and then replace that distribution group with a list of all the members who should be a resource delegate. To do this, follow these steps:
Obtain the list of current delegates by using the following cmdlet:
Remove the distribution group from the array by using the following cmdlet:
$delegates.remove("<Identity of distribution group to remove>")
Add a single user to the array (that is repeated for any additional users to add) by using the following cmdlet:
$delegates.add("<Identity of single user to add>")
Apply the changes by using the following cmdlet:
Set-calendarprocessing <room> -resourcedelegates $delegates
Migrate the room mailbox from on-premises to cloud, and then migrate all other delegates who are a member of that distribution group.