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A Complete Guide to Combine Two Office 365 Tenants After Merger

Raj | Modified: April 25th, 2023 | 6 Minutes Reading

Undoubtedly, there are several types of email services on Cloud but one of them is Office 365 developed by Microsoft. In the era of cloud computing, web-based applications are most important in the IT field. At certain times, users may face many challenges while merging two Office 365 tenants together. Therefore, in the upcoming section, we are going to discuss a step-by-step procedure to combine two Office 365 tenants in an absolute manner.

Techniques to Merge / Combine Two Office 365 Tenants

Users can combine two Office 365 tenants with the help of the given method. One is manual and the other one is a commercial solution. Let us proceed with a manual approach to merge two Office 365 accounts.

Manual Workaround

Before discussing the command to integrate Office 365 tenants together, it is important to keep some important things in mind as listed below:

Client considerations

  • For Outlook 2010/ 2013: Remove the account of MS Outlook.
  • For Outlook 2007/ 2010: During restarting, the email client will be configured by auto-discover and building the OST file once again.
  • For Lync Client: After the merge is done, you can add all contacts.

Preparation & Licensing of Tenant

  • There is a need to increase licenses in the targeted tenant of Office 365. This is necessary so that the mailbox of the source tenant to be consolidated into the targeted tenant.
  • Create an Administrator account in both target and source tenants. It is very useful in the process of merging two Office 365 tenants.

End-user interactions

For the interactions of merging with users in the organization, users must prepare themselves using a method described below:

  • Make a plan of interaction and start the merging process of the two domains and the modifications in service.
  • Once the consolidation process is done, the nickname cache must be cleared on the MS Outlook application.
  • Inform the user about the entire process to connect to the Outlook Web App (OWA) with the help of fresh login details in case of any issue after the merging process.

Preparation & Pre-migration Actions: 3 days before the Merger

Preparation of Domain

  • Users have to start the verification of the domain, on the tenant that is targeted for the email domain of the source tenant.
  • Another thing that needs to be accomplished is that in the targeted Office 365 admin center, add the source domain and in DNS, create a TXT record for verification

Note: The domain still needs to use in another domain, therefore the verification will fail.

  • After all these steps, a user allows the DNS record time to circulate. This whole process can take approximately 72 hours.

Scheduling of Merging

  • Users have to generate the master list of user mailboxes that are required to combine.
  • After this step, you can create the mailbox mapping.

Mail Exchanger (MX) Record Time to live test & Disable Directory Sync in Source Domain

Target tenant preparation

Target tenant preparation involves the verification of the source tenant in the target tenant. End-user needs patients at least 1 hour after the removal of the domain from the existing domain.

  • Using AD FS, users must have to configure the new domain in target for AD FS.
  • Start the activation of a target domain and allot licenses to a new user account.
  • Set the source as a primary email address.
  • Place the password on the domain mailbox, which is targeted when users are not accessing the AD FS or password synchronization feature.

Source tenant preparation

Users can remove the primary email domain from all objects available in the source tenant, before integrating into the target tenant

  • Now, in setting up the public website of SharePoint Online, place the website URL again to the initial domain.
  • Delete the Lync licenses in the source domain using the Lync admin portal.
  • By default, set the email id on the source mailbox of the initial domain once again and reset all email addresses on Resources, Rooms, and Distribution Lists to the initial domain in the source tenant.

After that, run the PowerShell scripts for the merge process:

Reset Office 365 bulk password

  • First of all, generate the CSV file with the name password.csv.
  • Now, put in the “upn” & “newpassword” columns in the created file (for e.g.: [email protected],Password2).
  • Run the below command of PowerShell:
    Import-Csv password.csv|%{Set-MsolUserPassword –userPrincipalName $_.upn -NewPassword $_.newpassword -ForceChangePassword $false}

Print MS Office 365 account with a specific address of proxy into CSV file


Bulk Create Room Mailboxes in Office 365


Remove Secondary Email Addresses from Mailboxes in Batch


Limitations of the Manual Approach

There are so many flaws in the manual approach. Some of them are mentioned below:

  • Users have to follow each command very carefully. As even a wrong step may lead to the removal of crucial data.
  • This manual process is very complex and lengthy.
  • Users should be aware of technical things and should devote as much time to task completion.

Use a Professional Tool  to Merge Two Office 365 Tenants

Now, we are ready to combine two Office 365 tenants, to do this tasks we have to use Office 365 to Office 365 Migrator. It is one of the best applications that helps to combine two Office 365 tenants without any hassle. With the help of this tool, users can merge Office 365 tenants, Accounts & domain users’ data. This application supports all the Windows Operating system and also keep all data intact.

Download Now    Purchase Now

Software Working Steps to Merge Two Office 365 Accounts

  • Step 1. Install and run the software on your PC
  • Step 2. Select Office 365 as source the and the destination.
  • Step 3. Choose the required workload and apply the date filter.
  • Step 4. Log in with source and destination admin credentials.
  • Step 5. Validate required permissions and click on start button.

Benefits of Combining Two Office 365 Tenants

  • Centralized Management: Combining two Office 365 tenants allows administrators to manage all users, groups, and resources from a single location.
  • Increased Collaboration: Merging tenants can enhance collaboration between different teams, departments, or companies by providing access to shared resources and applications.
  • Improved Resource Utilization: By pooling resources, administrators can make better use of available resources such as email, storage, and bandwidth.
  • Enhanced Security: Combining tenants can lead to improved security by allowing administrators to apply consistent security policies across all users and resources.
  • Cost Savings: Merging tenants can result in cost savings by eliminating the need for duplicate resources and reducing the number of licenses required.
  • Improved User Experience: A combined tenant provides users with a unified experience and a single identity, making it easier for them to access the resources and applications they need.

Also Read: How to Export Office 365 Mailboxes to PST using eDiscovery – Free Tutorial

Let’s Wrap Up

Office 365 is the best cloud-based suite that comes up with so many advanced features. At certain times, some users or organizations want to combine two Office 365 Tenants. For this, they start searching for a trustworthy solution, as data security is so important. Therefore, in this blog, we have discussed trusted solutions for merging two tenants of Office 365 suite. Users can follow any of the approaches as per their needs.