A Complete Guide to Combine Two Office 365 Tenants After Merger

Admin | June 2nd, 2020 | Office 365

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 an 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.

2 Best Techniques to Merge / Combine Two Office 365 Tenants

Users can combine two Office 365 tenants with the help of these two methods. One is manual and the other one is commercial solution. Let us proceed with 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 build 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 source tenant to be consolidated into 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 to users in organization, users must prepare themselves using a method described below:

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

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

Preparation of Domain

  • Users have to start the verification of domain, on tenant that is targeted for email domain of the source tenant
  • Another things that need to be accomplished is that in 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 source tenant in target tenant. End user needs patient at least 1 hour after the removal of 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 new user account
  • Set the source as primary email address
  • Place the password on domain mailbox, which is targeted when users are not accessing AD FS or password synchronization feature.

Source tenant preparation

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

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

After that, run the PowerShell scripts for merge process:

Reset Office 365 bulk password

  • First of all, generate the CSV file with name of password.csv
  • Now, put in “upn” & “newpassword” columns in created file (for e.g.: abc@org.com,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 Address from Mailboxes in Batch


Limitations of Manual Approach

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

  • Users have to follow each command very carefully. As even a wrong step may lead to 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.

An Efficient Solution to Merge Two Office 365 Accounts

To overcome all such limitations of manual method thus, users can opt for a reliable third-party tool such as Microsoft Office 365 to Office 365 Migrator. It is one of the best application that helps to combine two Office 365 tenants without any hassle. With the help of this tool, users can keep all duplicate emails away. This application supports all the Windows Operating system and also keep all data intact.

Download Now    Purchase Now

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 the data security is so important. Therefore, in this blog, we have discussed manual and automated solutions for merging two tenants of Office 365 suite. Users can follow any of the approach as per their need.