EHA customers that rely on the FOPE/EHA Directory Sync Tool (FOPE DST) to automatically synchronize Active Directory user accounts to the FOPE/EHA service should not use the Microsoft Online Service Directory Synchronization tool (MSO DST) after transition from EHA to Office 365. Doing so may over write settings which are required for message retention in your Office 365 mailboxes, for example this may cause the disabling of Litigation Hold. At this time there is no equivalent tool available for synchronizing your local directory users to Office 365. Microsoft is investigating solutions for a future release. Note that this only applies to you if you are using an On-Premises Exchange e-mail environment and you are journaling mail into Office 365 for your on-premises mailboxes.