Hybird Tenant to Tenant Migration - Keeping Same AD and Domains

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Hybird Tenant to Tenant Migration - Keeping Same AD and Domains

Alex Wan 1

Hello,

I have a large project I am working on for one of our clients with a new scenario for us.
We have done many Hybrid and tenant-to-tenant migrations for one reason or another. Our current client has the following scenario

Current environment Hybrid Exchange 2016 all mailboxes are in the cloud (DomainA.com and DomainB.com custom in use based on location)
There are over 4,000 mailboxes and not enough storage on-prem to offboard the mailboxes back onto on perm servers.

They want to move to a new Tenant to change the Tenant's name, i.e. current tenant is OldCompanyName.onmicorosft.com / OldCompany.Sharepoint.com.
The new Tenant they are requesting will be named based on the New Company Name, so their SharePoint URI is changed.

The main issue I'm foreseeing is the Mailbox and Archive GUIDs won't be the same as we are using a 3rd party tool to relicate all OneDrive, SharePoint and Mailbox data to the new tenant.
Has Anyone done a migration, that involved pointing Hybird Exchange On-perm to a new tenant (Rerunning HCW) and has the Mailbox and Archive GUID changes been an issue?

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Answer 1

Lucas Liu-MSFT 6,196

Hi @Alex Wan ,
According to the information you provided, your consideration is that you are using a third-party tool to migrate and worry about the mismatch between the GUID of the mailbox and the on-premises AD object after the migration. If I understand wrong, please correct me in time.

At this time, you should perform "hard match" and convert the GUID of the on-premises AD object to the "immutableID" in Azure AD, then writing that converted value directly into Azure AD.But before you proceed with this, you will still need to ensure that the UPN suffixes match the primary email domain on-premises and in the cloud.

For more information: Soft (SMTP) vs. Hard (immutableID) matching with Azure AD Connect and Dirsync soft matching vs hard matching
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.

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Alex Wan 1 Reputation point

2021-05-18T23:22:48.35+00:00

@Lucas Liu-MSFT
It's not the User Object matching to the new tenants User Object i'm worried about.

Example: if you were to off-board Office 365 to Exchange On-perm and the Archive GUID or Mailbox GUID did not match what is in Active Directory it would fail.

Lets say for my example, I complete the migration, cutover the Domains, AD-Connect to the new tenant. Enable AD-Connect Exchange Hybird sync and run Exchange Hybird connection Wizard so it connects to the new tenant.
This is where the problem comes in, the new tenants Exchange objects will have all new GUIDs that don't match the on-perm storaged info, I do not know if simply replacing the GUID attributs for msExch lines will correct the problem.

Just seeing if anyone else has done this and if they did something simliar to what i'm planning.
Lucas Liu-MSFT 6,196 Reputation points

2021-05-20T05:38:48.197+00:00

Hi @Alex Wan ,
According to your description, what you worry about is after the mailboxes in O365 are migrated to the new tenant. Can the new mailbox in O365 and the on-premises AD object not match correctly?
If so, then you could consider the "Hard matching" I mentioned above. This is when the on-premises account does not match the O365 account. Convert the GUID of the on-premises AD account to the "immutableID" in O365, and then writing that converted value directly into Azure AD. And then synchronize with Azure AD by using Azure AD connect. For more information you could refer to the articles I provided above.

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Lucas Liu-MSFT 6,196 Reputation points

2021-05-25T08:47:34.147+00:00

Hi @Alex Wan ,
Do suggestions above help? If the issue has been resolved, please click “Accept as answer” to mark helpful reply as an answer, this will make answer searching in the forum easier and be beneficial to other community members as well.

Thanks for your understanding.

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Lucas Liu-MSFT 6,196 Reputation points

2021-05-28T09:25:09.593+00:00

Hi @Alex Wan ,
I am writing here to confirm with you how thing going now?

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Answer 2

Ankit Shukla 1

in sequential order (an ideal procedure) -
Disable Directory Sync
Complete your cutover ( tenant to tenant data move using whatever procedures you have planned, PST, Bittitan , etc etc etc )
Reconfigure Directory sync to Point to New Tenant (Azure AD)

Alex Wan 1 Reputation point

2021-05-16T16:36:55.797+00:00

That's a standard tenant to tenant migration, the issue with this one is there is an On-Perm Exchange server in Hybrid configuration. It has maintained mailbox attributes in the on-prem Active Directory such as the mailbox and archive GUIDs. I have a plan moving forward but want to confirm someone else has done a similar scenario and that my plan is going down the right path.

My current plan is to export all new tenants' mailbox and archive GUIDs and create a basic script to change the on-prem Exchange attributes to match the new tenant's values, perform the standard tenant-to-tenant steps and re-run Exchange HCW once the domain has been moved to the new tenant.

What happens normally if the on-prem exchange mailbox and archive attributes don't match that of Exchange online in a hybrid setup is you get correlation errors, locking the Azure AD side for the user.
Kin Lee 0 Reputation points

2026-04-07T15:01:02.7833333+00:00

Hi Alex,

Wonder if the above plan worked for you? I am running in the similar situation and came across this thread.

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Hybird Tenant to Tenant Migration - Keeping Same AD and Domains

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