Remove Hybrid Configuration or undo Hybrid Configuration

Question

Hello experts,

I have a quite rare scenario on the following:-

1. We have moved few mailboxes from exchange onpremise to exchange online
2. Already performed the Azure AD sync and configuraton, exchange hybrid wizard and 0365 integration
3. Working as expected but only a few users since it is still not yet roll out.
4. All mailflows, Distribution list, users are sync and assigned license users is able to carry out their email activity as per normal

However, the factory plant received an instruction from the HQ which is on another country to roll back all the configuration which was done as they want to have their own tenant and use their exchange servers (which consists of couple of exchange servers based on that location). so we have to move back all the mailboxes back to onpremise and undo the deployment which was done.
All the scenario which i found is removing hybrid configuration after all the mailboxes moves to exchange online but my scenario is different where basically move back all to onpremise and remove the hybrid configuration

Here is what I have so far:-

1. Move back all the mailboxes from exchange online back to exchange onpremise - Done
2. Unassigned the 0365 business standard license from the users
3. Change back the UPN in onpremise
4. Remove Hybrid configuration (Remove-HybridConfiguration)
5. Remove O365 Send Connector from onpremise exchange
6. Remove the O365 Accepted Domain from onpremise exchange
7. Remove the Connector in exchange online (connector which is back to onpremise)
8. Remove the organization sharing in exchange online

My objectives is to remove the hybrid on the exchange first completely before going to the next phase which is unsycn all the users from onpremise AD and uninstall Azure AD

After performing step 1-8 I can still see the following:-

1. Get-IntraOrganizationConnector and Get-RemoteDomain still showing the exchange online (O365). How do we remove this setting and what is the impact after removing those?
2. How do we remove the O365 routing address on the users who is already in exchange onpremise. I can see some additional email addresses as below in the email address tab of the users:-
   username@Monique gmx .domainname.onmicrosoft.com
   ******@domainname.onmicrosoft.com
   and couple of x500 email address which generated earlier
3. I have remove the O365 routing address in the email address policy but seem it is not taking effect
4. Amny impact when removing x500 email address

Thank You
6. List item

Answer 1

Hi @Niven Peter ,
1.About Get -IntraOrganizationConnector and Get-RemoteDomain.

1)We could run the following command to remove the intra Organization connector. Based on my knowledge, the intra organization connector is used to share free/busy information in hybrid deployment, and if OAuth is configured, it also needs to be disabled when the Hybrid configuration is uninstalled. For more information please refer to the Scenario one in this article: How and when to decommission your on-premises Exchange servers in a hybrid deployment

From the on-premises Exchange server, open the Exchange Management Shell:

Get-IntraorganizationConnector -Identity ExchangeHybridOnPremisesToOnline | Set-IntraOrganizationConnector -Enabled $False  

Connect Windows Powershell to Exchange online:

Get-IntraorganizationConnector -Identity ExchangeHybridOnlineToOnPremises | Set-IntraOrganizationConnector -Enabled $False  

2)The remote domain is used to set certain specific settings for a specific domain in terms of OOF, automatic forwarding, etc. By default, there will be a remote domain with a scope of all domains. The remote domain set by yourself will take precedence over the default remote domain. But if you don’t need to use it now, you can run the following command to remove the remote domain. For more information you could refer to: Remote domains in Exchange Online

Remove-RemoteDomain -Identity <>  

2.About the secondary SMTP address, I found a script could bulk remove the secondary SMTP address. I test it in my lab environment and successfully deleted SMTP address I set. You could replace "*contoso.com" in the script according to your needs. For the specific script: Bulk remove secondary SMTP address with PowerShell
Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

3.The X500 address is synchronized from Exchange online to the local Exchange in a hybrid deployment. If we don’t add the X500 address to the user’s attributes, when dealing with the old mail items, the sender may receive NDR (Non-delivery Report) reporting that the specific recipient doesn’t exist. According to your situation, I think it can be deleted, but in order to prevent accidents from happening, I suggest you back up the X500 address of one of the user’s mailboxes, and then delete it. Then check whether the sending and receiving of the mailbox is normal.

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Answer 2

Hi Lucas,

Thank you for your answers and the test that you carried out in your lab. I have done the rollback by the help of Microsoft and validate the rollback process. As for the smtp routing address, the Microsoft tech support mentioned that it will not affect if the address is not removed. so for now, I leave the smtp routing address for now since it is just an additional routing.

Thank you