We have an onsite Hybrid 2010 Exchange server. All of our mailboxes have now been moved over to Office 365. We are using DirSync to Sync our users and Passwords. I fully understand that I will need to use ADSI Edit to modify mail attributes if I decommission the onsite server. I also know the Non-Recommended/Recommended decommissioning method from MS.
My issue with that method is you don't uninstall Exchange, which will leave all kinds of old data in Active Directory. My fear with uninstalling Exchange is that we may lose the mail enabled user attributes within AD; which would result in downtime and possible data lose while I try to recreate all those settings.
Does anyone know a clean way to fully decommission an on premise Exchange server that is currently setup as a Hybrid, as well as cleaning AD of all the old/unnecessary data?