Change AD Connect synced accounts to Exchange Online

Question

Hello

We are using AD Connect to sync our on-premises AD to Azure AD.
We also have an Exchange on-premises server so mailboxes are not currently in the cloud. It is not yet set up in full hybrid mode.

We have had an outage to the onsite infrastructure which may take some time to resolve.

I have been asked about the possibility of enabling online mailboxes in O365 for some or all of the users. As the business is heavily reliant on email this would allow staff to at least use email in the meantime. We would then need to look at importing existing email from the onsite Exchange server when the connectivity is restored. It's not something I really want to do but I need to check if it's possible.

Is this something that can be done without causing more problems later on, apart from the obviously major hassle of exporting and importing mailboxes later ?

If it can be done what would be the process ? I assume AD Connect would need to be disabled but I don't know what steps we'd need to follow to do this correctly, enable the online mailboxes, then re-enable AD Connect later (when connectivity is restored) without creating inconsistencies in accounts.

Thanks

Answer 1

Hi,

It is possible to migrate some or all of the mailboxes in Exchange online in a hybrid environment. The move of the mailbox to Exchange online can be done without loss of emails and side impact on the client side. But you should restore the connection and the synchronization between your on-promise Active directory and Azure active directory.

Ways to migrate multiple email accounts to Microsoft 365 or Office 365

Once you still use your on-promise active directory for authentication and GPO, you should keep Azure AD connect. In hybrid infrastructure , Azure AD connect is required to ensure the Single Sign on and the synchronization between Azure active directory and your local active directory.

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Answer 2

Hello

Thanks for the reply. But I don't think you have read my post correctly.

The Exchange is NOT currently in hybrid mode. Plus, we cannot migrate mailboxes as the on-premise Exchange server is unavailable.

There is currently NO connectivity between the on-premise environment and O365

My question was - can we enable user mailboxes for online use without creating unfixable problems later on and, if so, how do we do this ?

Thanks

Answer 3

Hi @Cap Sam

Thank you for asking this question on the **Microsoft Q&A Platform. **

Short answer, yes you can create the mailbox in Exchange Online,

You should keep running the Azure AD Connect, you still have some mail properties in the Domain Controller.

After you recover your on-premises server, the effortless way is migrating the old mails via import PST

Good luck.

Hope this helps,
Carlos Solís Salazar

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Please and if any of the above helped so that, it can help others in the community looking for remediation for similar issues.

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Answer 4

My question was - can we enable user mailboxes for online use without creating unfixable problems later on and, if so, how do we do this ?

Sorry for the misunderstood , before answer to this question , you have to define which authentication method you will want to use to access on Exchange online?

If you want keep your local Active directory the unique provider for authentication for all resource in could and local because you have already applied policies like password policy , in this case you should deploy Azure AD connect to ensure the synchronization and Single -Singn- On.

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Answer 5

Hi

So from the answers so far it seems this is something that can be done. But I was hoping there might be an existing step by step process to do this if someone has done this previously.

I don't know what steps we need to follow to ensure we know how to do it and also so we don't create further problems.

Thanks