The ActiveSyncDevice Cannot be Found–unable to delete Active Sync Devices in Exchange 2010
This error occurs when inheritable permissions are not enabled on a mailbox. You will see this error when trying to remove an ActiveSync Device:
To fix this, first enable
Advanced Features in ADUC:
Then open the user’s properties and browse to the Security tab. Click
Advanced and then place a check in the box labeled
Include inheritable permissions from this object’s parent. Click OK twice to apply. Wait for AD to replicate to your GCs then retry the action in Exchange. It will now remove the device successfully.