Office 365 Tenant to Tenant Migration – Step by Step Guide

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Introduction: Office 365 Tenant to Tenant Migration refers to exporting data from one custom domain Microsoft account to the other Microsoft account. Here, you are exporting emails, contacts, Notes, and other data to another Office 365 domain account.

This type of migration is generally needed during the acquisition or division of organizations. So, employees will require the email address with a custom domain name of the new organization. There are different approaches through which you can migrate your Office 365 data from one account to another.

Why Do You Need Microsoft 365 Tenant to Tenant Migration?

The most significant reason for Office 365 tenant to tenant migration is when organizations split, merge, or rebrand. The employee’s email address must be recognized with the new brand name.

How to Perform Office 365 Tenant to Tenant Migration?

The procedure of Microsoft 365 Tenant to Tenant Migration contains several stages and is quite complicated. Moreover, before initiating the migration, you need to perform certain pre-migration operations to ensure successful migration.

Let us check what the Pre-migration stages are.

Pre-Migration Setup

Before initiating the Office 365 tenant to tenant migration without tool, you need to perform the below steps. They are the prerequisites for successful export.

Step 1: Prepare Domain for Migration

  • Your destination domain must have sufficient space to import the data from the source domain.
  • An equivalent or higher Office 365 premium plan is mandatory for the destination account to conduct the migration.
  • Admin account permissions are necessary for both the Office 365 accounts. Sometimes, you may use additional tools to create an admin account of an existing Microsoft account.
  • You need to create user mailboxes, resource mailboxes, and distribution groups in the destination account. These mailboxes should be similar to those of source email accounts.
  • You may require to perform the AD DS consolidation to synchronize the source domain with the destination domain.
  • At last, you need to train the end-user regarding the post-migration procedure.

Step 2: Verify Your Domain

  • First, verify the destination Office 365 domain.
  • Now, add the source domain into the target domain and add the TXT file into the DNS record.

Note: The source Microsoft account should not be added to another account. Otherwise, the migration will fail.

Step 3: Schedule Office 365 Tenant to Tenant Migration

  • You have to create a CSV file for mapping user mailboxes from the source account to the destination account. You can download a sample CSV file to check the structure of the mapping file.
  • On the Mail Exchange (MX) Records, check the lowest TTL value of the source Office 365 domain.
  • From the Admin Center, stop the Directory synchronization for the source email account.

Step 4: Migrating Mailbox Data

#1. Stop Mail Flow to the Source Domain

Block the mail flow from the destination account to the source account. For this, change the MX Record of the source account to an unattainable value. The value can be identified from the TTL value noted previously.

#2. Source Domain Setup

  • Delete the primary domain from all the source objects before conducting the migration.
  • Configure the initial Office 365 email address as the default email address.
  • Use the Lync Admin Portal to delete all Lync licenses from the source account.
  • After that, make the initial Office 365 domain as the default account for the distribution list, resources, and chat rooms.
  • Remove the destination Office 365 account from all the objects.

#3. Destination Domain Preparation

  • The first thing you have to do is verify the source account in the destination domain.

Note: This process should be performed after one hour from the previous step.

  • After that, configure the CNAME and new domain in the destination account for AD FS.
  • Next, set up all the user accounts in the destination domain and assign a license.
  • Now, configure the source domain as the primary email address.
  • After the user mailboxes become active, set the MX records to the new Microsoft Office 365 email address.
  • Check the mail flow of this new Office 365 account.

Microsoft 365 Tenant to Tenant Migration

There are two different modes for Office 365 tenant to tenant migration based on several user mailboxes. You can opt for any as per your preference.

#1. For Less than 500 User Mailboxes

Export Email, Contacts, and Calendar separately. Set criteria, like date range, to limit the migration.

#2. For More than 500 User Mailboxes

The Multi-Pass method is suitable for migration for more than 500 user mailboxes. It migrates data in multiple batches.

Better Alternative to the DIY Technique

DRS Office 365 Email Backup tool is the most preferred solution for Office 365 Tenant to Tenant Migration. You need not perform the complicated steps of the manual procedure. Using this utility, you can export your data in a few simple steps. Moreover, the application provides you with numerous advanced features. Also, the application has an interactive user interface; you can use the software without additional assistance.


In this article, you have learned different ways for Office 365 tenant to tenant migration without tools. The DIY technique for migration is quite complicated and time-consuming. Also, the chances of data loss are high in this mode of migration. Therefore, we suggest the most reliable and fast solution. The professional Office 365 Backup tool helps you export your data in a few simple steps without any data loss.

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