An Overview – Tenant to Tenant Migration Office 365 Microsoft

Because of the rising number of businesses using Office 365, several users are looking for Office 365 tenant migration. Various reasons can be there but the most common are acquisition or merger events.

Tenant migration in O365 is an intricate process for some users to perform, as it involves various dependencies with production users on each Tenant, users must take extra care when making any technical change.

Before initiating the Office 365 migrate between tenants process, careful planning is required. Otherwise, chances of losing data will become high and at some point, users might struggle and waste a lot of time. So in this article, we’ll be explaining some pre-migration steps which is required for tenant migration. 

In What Scenarios Does a User Requires Tenant to Tenant Migration Exchange Online

Cloud adoptions by many firms are increasing every day. There are several cases in which it leads a user to migrate to a new cloud tenant. We have discussed some of the reasons that are:

  • Microsoft 365 Tenant Name Change.

Microsoft doesn’t provide any option to change the tenant’s name once it has been given. This means that it is crucial to select the right name before creating a tenant. If a user wants to change the tenant, then it requires creating a new one and transferring all the data to a new tenant.  

  • A Merger or Acquisition.

Dealing with a company merger or acquisition can be a tough job as this includes moving data to Microsoft 365 or merging tenants. Moreover, there are several cases users can consider at the time of mergers and acquisitions.

Generally, in a merger two companies merge and becomes a single company so, they have to keep both firms O365 account data in one place.

While in an acquisition, bigger firms acquire the smaller company to increase their business. In this case, all the existing data of the smaller firm needs to migrate to the bigger company that acquired them.

Pre-Migration Steps for Tenant-to-Tenant Migration Exchange Online

Step 1. Domain Preparation

Follow the steps carefully to Prepare the domain for migration

  • User needs to ensure that they have enough licenses for the target Microsoft 365.
  • Then the user should create O365 admin accounts in both the source and destination for a smooth migration process.
  • Create user mailboxes, room mailboxes in the destination account.
  • Perform AD DS consolidation using AD DS tools and sync source domain with the target domain manually or using synchronization.
  • Train your end users regarding the post-migration use of Microsoft 365.

Step 2. Domain verification

  • Begin the verification of the destination tenant domain in Microsoft 365.
  • In target office 365 admin center add a source account and then create TXT records in DNS.

User must ensure the domain is in use only by one tenant otherwise, the verification will fail. After completing these steps, it will take around 72 hours to apply the changes.

Step 3. Migration Scheduling

  • Make a list of user mailboxes that has to move and create a CSV file for mapping.
  • Note down the lowest value of TTL on MX record (of the primary email domain).
  • Disable directory sync for source tenant (from Office 365 admin center) to avoid sync of any modifications in source tenant account AD DS to Microsoft 365 platform. It can take almost a day to complete the disabling process.

Step 4. Migration Stage

  • Restrict incoming mail flow

Now the user must stop the incoming mail flow to the source tenant by changing the primary MS record by using a third-party service. As the user has got the lowest value of TTL on the MX record (of primary email domain) in their preparation step, the user can plan the time of this step easily.

  • Source Tenant Preparation

Before we begin the tenant to tenant migration office 365 Microsoft process, the primary mail domain should be erased from all objects in the source tenant.

  • Re-configure the default email Id to the initial email Id of Office 365.
  • delete all the Lync licenses from the source tenant using the Lync Admin Portal.
  • Reset the default email address of distribution lists, rooms, to the initial domain.
  • Delete the secondary email address from all tenant objects.
  • Now, in Windows PowerShell, run the command Get-MsolUser -DomainName that will retrieve all the objects using the source email address or refusing the removal.

Destination Domain Preparation

  • It involves verifying the source tenant in the destination domain.
  • Setup the auto-discover CNAME.
  • When users use AD FS, they will have to configure a new domain in the target tenant for AD FS.
  • Then activate the new user accounts in the destination domain and assign the licenses.
  • On the new users, set the source domain as the primary email Id (do it using Windows PowerShell). Also, convey the passwords to end-users if required.
  • When the user mailboxes are active, change the routing of the mail and point the MX record to the destination Office 365 email address.
  • Check the mail flow in and out of the destination tenant.

Begin the Migration

Now, this is the time to decide on the migration method. Migration can be accomplished using PowerShell scripts. However, it might become complicated for some users. IT experts suggest users to look for an alternative solution as it takes complete control over the migration process along with efficient processes automatically.

Experts Recommended Technique for Tenant-to-Tenant Migration Exchange Online

After following all the premigration steps we suggest users to use the In-demand Office 365 to Office 365 Migration Tool. Follow the steps to use this tool which will help users for O365 tenant migration.

  • To begin the migration process, the user has to download and install the tool. After that they have to choose both source and destination as Office 365.
  • Here, users can decide which categories they have to choose in Resource & Workload section. Also, users can apply the date filter if they want.
  • Now in the Source tab, type the admin login credentials and press the Validate button to validate.
  • In the destination section type the admin destination email address and application ID and hit on the Validate button to validate all the permission. Then press Next button.
  • Next, in the resource section, you can add users from the source account who needs to migrate using several ways like Fetch Users, Import Users, Download Templates.
  • In the next step, users need to type the email address of destination user mailboxes.
  • Now hit on the Validate button to validate the permissions.
  • After successful validation, press the Start button to begin the tenant to tenant migration office 365 Microsoft.  


In this article, we have talked about the process for the tenant to tenant migration office 365 Microsoft. Here, we have mentioned the pre-migration steps and a professional solution to execute the migration process without losing any data.    



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