Hybird Tenant to Tenant Migration - Keeping Same AD and Domains

Alex Wan 1 Reputation point


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?

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Ankit Shukla 1 Reputation point

    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)

  2. Lucas Liu-MSFT 6,156 Reputation points

    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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