Consider the following scenario:
You create a mail-enabled universal security group in a Microsoft Exchange Server 2010 environment.
You create a resource mailbox, such as a meeting room.
You add the group as a resource delegate for the resource mailbox by running the Set-CalendarProcessing cmdlet.
In this scenario, the members of the universal security group do not have permission to delegate the resource mailbox.
This issue occurs because the group is added to the Active Directly object attributes of the resource mailbox. However, the group is not added to the Access Control Entry for the respective folders of the resource folder.
To resolve this issue, install the following update rollup:
2866475 Description of Update Rollup 2 for Exchange Server 2010 Service Pack 3
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about how to configure a delegate on a resource mailbox, go to the following Microsoft website:
How to configure a delegate on a resource mailboxFor more information about how to manage resource mailboxes and scheduling in Exchange 2010, go to the following Microsoft website:
How to manage resource mailboxes and schedulingFor more information about Access Control Entries, go to the following Microsoft website: