My customer has a SBS 2008 Server and uses the built-in Exchange Server 2007. I migrated their mailboxes to Office 365 via a cutover migration. Now comes the impossible part. Their workstations are a mix of WIndows 7 and WIndows 10. Outlook on those workstations is a mix of 2010 and 2013.
I can manually configure their Outlook to point to Office 365 but it will only stay for maybe 4 hours and reverts back to their Exchange Server. Simply opening Outlook and letting it sit it reverts back. I can tell when the Outlook 2010 workstations revert back because a pop-up asking for their email address and password keeps popping up. I can tell when the Outlook 2013 workstations revert back because they get a pop-up stating "the microsoft exchange server administrator has made a change that requires you to quit and restart outlook". At that point Outlook has reverted back to pointing to their Exchange Server.
I have tried stopping all the Microsoft Exchange services on their Exchange Server. Nothing I have tried works. I cannot keep Outlook pointed to Office 365. It keeps automatically reverting back. My guess is that I need to change the autodiscover services on the Exchange Server but that is just a guess. Does anyone know how to do this?