Add AADConnect/DirSync after O365 cutover migration

New Contributor

Looking at doing an Exchange 2010 to O365 cutover migration in a few weeks and wanted to make sure I can use AADConnect/DirSync AFTER the migration is done/licenses applied/etc. It is ~50 users and not a lot of mailbox items.


The plan is to do the following:

  • Connect Office 365 to Exchange 2010 server (already have Outlook Anywhere and a legit cert)
  • Start mailbox migration batch
  • Grant licenses to mailboxes
  • Let that sit for a couple of days (start mid-week)
  • Cut over DNS (Saturday)
  • Final mailbox migration
  • Stop mailbox batches
  • Set up AAD Connect
  • After a week, remove mailboxes and decommission Exchange. 

Do I have that correct? My LAST step should be to set up AADConnect/DirSync? If so, anything I need to be aware of? Just make sure the SMTP attribute in AD matches what is in O365? Is anything going to happen after I remove Exchange? 

5 Replies

Hi Mark,


You can do that, but you will not have support from Microsoft because you need to maintain the Exchange, if you uninstall your Exchange you cannot have AD Connect fully supported.


You can read more here and here


You will need to install a new Exchange Hybrid a Hybrid License, you can read more here

I am attempting the same in a few weeks and from what I understand you are correct in the case of a cutover migration. I have done a hybrid migration in the past and I couldn't remove my on-premises Exchange. Hence I will be doing cutovers from now on.

We currently have AD Sync running inside our network with no Exchange Server locally.  We don't have any problems however its a pain when we need to make user changes  as we need to use the attribute editor in AD, can be a pain.


We did not want a local Exchange Server as the end goal was to migrate to 365 removing the local hassle of managing a local Exchange box. which has been done.


Without installing a local exchange server is there anything else we can install / do to help managing users (without using Attribute editor?)

Hi Roger,


You will need Exchange Hybrid to have full support from Microsoft, and depending your license you do not pay Exchange Server, you can view and request the key here 

 Hey @Mark Valpreda 

How was finally you did the setup? i´m about to do the same cutover migrtion, and i have the same doubt about when deploy AAD Connect and if going to have problems with that.


I hope you can answer my concern