upon employee termination the manager should NOT have access to the OneDrive account
If the My Site Cleanup is enabled and a manager is specified for the employee in AD, when that employee is terminated the manager is given access as a Secondary Owner. This allows the manager to view/edit/delete information located in the employee OneDrive account. This can be very dangerous in a couple of ways. First - Confidential or private HIPPA information might be stored in the One Drive account. Second - If there is a legal situation concerning the terminated employee, the manager has the ability to change or delete documents that should be archived unchanged - not knowing if for some reason they might be needed for a legal situation at a later date. With the manager's ability to access the documents the company cannot guarantee the information was preserved untouched.
