We have Exchange 2010 on-premises for our organization emails. Now we plan to migrate to Office365. The plan is to migrate all the mailboxes to cloud while keeping Active directory synchronization enabled (The on-premises setup will be remove).

Hybrid deployment should be used if both on-premises and cloud bases servers will be used so Cutover Exchange Migration suites for this operation. But the tutorials I have gone through say that Cutover Exchange Migration will fail if Active directory is synchronized before the migration.

My questions are

1: While migrating from Exchange 2010 to Office365, can we sync the active directory after the migration? Will we be able to manage users created by Cutover migration process?

2: Can we use Hybrid Deployment in this scenario and then remove our on-premises exchange server?

2 Answers 2


I got answer from microsoft technical forum.

We can not synchronize active directory with office 365 before migration because the cutover process itself creates the user objects.

  1. Once the migration is completed, you are free to use DirSync to sync your on-premises AD to Office 365.
  2. Hybrid deployment is required for staged migration, but there is no reason you can't remove Exchange after the migration is complete. We do recommend, however, that you keep exchange 2010 installed so that you can manage users, etc. post-transition, through an easy interface instead of having to manage everything through attribute manipulation.

Here is the reference link:- http://social.technet.microsoft.com/Forums/en-US/onlineservicesmigrationandcoexistence/thread/2b20b7e5-15e8-4f79-a6b9-8046b962c382

  • If you solved the problem stated in your original question, you should mark this answer as accepted answer to help future visitors.
    – Benny Skogberg
    Apr 1, 2014 at 6:24

The best approach here is to synchronize after migration. Please refer to this article that defines step by step processes to configure and set up synchronization that automatically updates. http://onlinehelp.microsoft.com/en-us/office365-enterprises/ff652557.aspx

The first time you synchronize your directories, a copy of your local users and groups is written to your Office 365 directory. From then on, Active Directory synchronization checks for changes to your local Active Directory and updates your Office 365 directory with those changes.

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