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How to Combine Two Office 365 Tenants After Merger – A Complete Guide

Published By Mohit Jha
Nimisha Ramesh
Approved By Nimisha Ramesh
Published On May 6th, 2024
Reading Time 8 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.

Different 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.

5 Simple Steps to Merge Two Office 365 Tenants Quickly

  • Step 1. Install and run the software on your PC
  • Step 2. Select Office 365 as source and 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.

Manual Workaround to Combine Two Office 365 Tenants After Merger

Before discussing the command to integrate Office 365 tenants, 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 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 service modifications.
  • Once the consolidation process is done, the nickname cache must be cleared in 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 be used 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 it 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, generate the CSV file with the name password.csv.
  • Now, put in the “upn” & “new password” columns in the created file (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

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Limitations of the Manual Approach to Merge Two Office 365 Tenants  

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

  • Users have to follow each command very carefully. 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.

Also Read: How to Forward Emails to Multiple Accounts Office 365?

Use a Professional Tool to Combine Two Office 365 Tenants After Merger

Now, we are ready to combine two Office 365 tenants, to do this task 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 Windows operating systems and also keeps all data intact.

Download Now    Purchase Now

Software Working Steps to Merge Two Office 365 Accounts

Step 1. Download and run the above-mentioned tool on your local computer. Select Office 365 as the source and destination migration platform.

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Step 2. Now enable the required workload from the given options such as emails, contacts, calendars, and tasks. Also, apply the date filter if required. Click on the next button.

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Step 3. Provide source and destination Admin Email and Application ID and validate the required permissions. Then click on next.

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Step 4. Select the required users from the given list and validate the required permissions.

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Step 5. Once all the required permissions get validated then click on the start migration button to combine two Office 365 tenants safely.

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Benefits of Combining Two Office 365 Tenants

  • Easy Management for Admins – When we combine two or more Office 365 tenants it allows IT or Office 365 admins to easily monitor and manage all the resources from a unified location. These include users, groups, storage quotas, special permissions, and other resources.
  • Enhances Collaboration – When we have multiple o365 tenants then the users from each tenant act as guest users to others. Which makes it complex to streamline data transfer and permission management. This eventually affects the overall collaboration, to overcome this combining them into a single tenant eliminates the hurdles of guest users since all users are now associated with a single tenant.
  • Right Usage of Resources – In a single tenant it becomes a breeze operation to manage resources efficiently, admins can better use available resources such as email, storage, and other required permissions. This eventually optimizes the overall cost management and improves ROI.
  • Systematic and Regular Security Implementation – Consolidating multiple tenants into one tenant leads to improved security implementation by allowing admins to enforce and deploy consistent security policies among all users and resources. These include MFA and retention policies for accounts, antiphishing, antispam, antimalware for email, etc.
  • Cost Optimization – Combining multiple tenants also leads to overall cost reduction as multiple tenants have their different plans and removing them reduces the cost of separate plans accordingly.

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 with countless 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 the Office 365 suite. Users can follow any of the approaches as per their needs.



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