In Microsoft Office 365 Dedicated, you cannot enable or disable a mailbox for Microsoft Exchange Unified Messaging (EUM) by using integration administrative scripts that are provided with on-premises Microsoft Lync voice.
This issue occurs because these scripts require permissions to update objects in the managed and source environments and cannot run correctly if the permissions are missing.
Microsoft provides the integration administrative scripts to help enable and disable mailboxes for EUM. When you enable or disable a mailbox for EUM, the managed mailbox is changed, and the EUM proxy addresses are added to both the managed object and the source object. These proxy addresses make sure that the Lync on-premises servers can route the mailbox when a call has to move to a voice mail message. The proxy addresses may resemble the following: