Synchronizing the Send as and Full access mailbox permissions is very time-consuming. Therefore, the functionality is disabled by default. To synchronize the mailbox permissions, you must customize the synchronization project.
- 
In the Initial Synchronization workflow, enable the Mailbox Permissions synchronization step.
 - 
In the Provisioning workflow, enable the Mailbox Permissions synchronization step.
 
To enable synchronization steps
- 
In the Synchronization Editor, open the synchronization project.
 - 
Select the Workflows category.
 - 
Select a workflow in the navigation view.
 - 
Click
in the workflow view's toolbar.
 - 
Deselect the Disable check boxes on all synchronization steps that you want to enable.
 - Click OK.