OnPrem Exchange to Office 365 Migration

New Contributor

Hi there,

Current Scenario: We have an onprem Exchange with 10 users, used Azure AD Connect to Sync users to Cloud for using Exchange Online Protection & ATP.

But now we are planning to migrate all users to Office 365 using cutover migration.

Now, I'm not sure if the cutover migration will try to recreate the accounts and fail or if it will just migrate in the already existing accounts with the correct mail address.

Any help or recommendation is greatly appreciated.

3 Replies



Hi, if you have on-premises Exchange and are already syncing your AD to Azure AD with AADC, then I would recommend using the Exchange hybrid method to migrate your mailboxes instead of the cutover migration.  Appreciate that you only have 10 mailboxes, but my general rule of thumb is that "if you can use hybrid, then you should use hybrid".  The reasons for this are;


1). Better user experience when finalizing the migrations

2). Outlook just reconnects and uses the existing OST file so no need to download all the mail again

3). When syncing AD to Azure AD, it is recommended and supported practice to retain at least one Exchange server in your environment to manage attributes and take care of SMTP relay


Not sure what version of Exchange you are running, but if you get O365 Enterprise licences for your users, then you will be able to get a free hybrid licence key for Exchange 2016.


Hope this helps.

@PeterRising Thanks Peter for your inputs.


We are planning to get read off OnPrem Exchange completely as soon as all the users are on Cloud.


But as I read with hybrid migration we will still need to keep OnPrem Exchange running right?


Thanks again.



Correct yes, if you want to remain in a supported position by Microsoft.