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Office 365 Tenant to Tenant Migration Step by Step Guide

Himanshu Goyal
Himanshu Goyal Updated On - 30 Dec 2020

A tenant in Office 365 is the domain account attached to the Office 365 Suite. A tenant administrator can use all the features given in the subscription. In business-merger scenarios, the mailboxes need to be moved to another tenant. The migration is not a linear process; you need to do some preparation, meet some prerequisites, and own licenses.

So, here we are going to discuss some basics that can help you migrate mailboxes from one Office 365 tenant to another. Also, here we’ll talk about how you can plan the migration.

Instant Solution

Migrate mailboxes, public folders, & archive mailboxes from one Office 365 tenant to another using a professional Kernel Office 365 Migration Tool.

A Simple Approach to Office 365 Tenant to Tenant Migration

The Office 365 tenant to tenant migration is performed using PowerShell scripts or third-party tools. Before that, there is an Office 365 Pre & Post Migration checklist you should keep in mind.

Pre-migration Stage

Step 1. Domain Preparation

Prepare the domain with the following steps:

  • Ensure that you have enough licenses for the target Office 365.
  • Create admin accounts in both the source and target to perform the migration smoothly.
  • Create user mailboxes, room/resource mailboxes, and distribution groups in the target.
  • If needed, 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 Office 365.
Step 2. Domain verification
  • Start verification of target tenant domain in Office 365.
  • Add a source domain in the target Office 365 admin center and create TXT records in DNS.

Make sure the domain is in use only one tenant. Otherwise, the verification will fail.

After performing these steps, it will take around 72 hours for the change to be seen.

Step 3. Migration Scheduling
  • Generate a list of user mailboxes that are to be migrated and create a CSV file for mapping.
  • Note the lowest value of TTL on MX record (of the primary email domain).
  • Disable directory sync for source tenant (from Office 365 admin center).
Step 4. Migration Stage

  • Stop inbound mail flow

    Stop inbound mail flow to the source tenant by changing the primary MS record to an unreachable value or by using a third-party service. As you have noted the lowest value of TTL on MX record (of primary email domain) in your preparation step, you can plan the time of this step easily.

  • Source tenant preparation

    Before moving the Office 365 mailbox to another tenant, the primary mail domain should be erased from all objects in the source tenant.

    • Reset the default email address to the initial email address of office 365.
    • Remove all the Lync licenses from the source tenant with the help of Lync Admin Portal.
    • Reset the default email address of distribution lists, rooms, resources to the initial domain.
    • Remove the secondary email address from all tenant objects.
    • In the Windows PowerShell, run the command Get-MsolUser -DomainName that will retrieve all the objects still using the primary email address or refusing the removal.
  • Preparing the target domain

    It involves verifying the source tenant in the target domain (do one hour after the previous step).

    1. Configure the auto-discover CNAME.
    2. When you use AD FS, you’ll have to configure a new domain in target tenant for AD FS.
    3. Activate the new user accounts in the target domain and assign licenses.
    4. On the new users, set the source domain as the primary email address (done using Windows PowerShell). Also, decide on communicating the passwords to end users.
    5. When the user mailboxes are active, change the mail routing and point the MX record to the new Office 365 email address.
    6. Test the mail flow in and out of the target tenant.

Begin the migration

  • When you have 500 users or less, migrate the mail calendar and contacts separately to the destination tenant mailbox. For email migration, limit the migration by any criteria like a date.
  • When you have 500 users or more, use the multi-pass method to migrate the contents in multiple batches. You can migrate only contacts, calendars, and a single week of data.

Now it is time to decide on the migration method. You can also decide on the type and amount of data to be migrated. Migration can be accomplished using PowerShell scripts. However, third-party migration tools are recommended as they offer complete control over the migration.

What Expert Think About Kernel Office 365 Migration Tool?

While migrating data from one tenant to another, the last thing you would want is losing data your data. Most migration experts recommend using a reliable and secure migration tool for Microsoft 365 tenant to tenant migration because it assures you to move your data without corrupting it. Even after migration, the data will be present in the same structure and format.

Kernel Office 365 Migration tool – For a quick and easy tenant to tenant migration

Kernel Office 365 Migration is an advanced tool that is specially designed for the Office 365 tenant to tenant migration. It allows users to easily migrate every Office 365 mailbox from one tenant to another. It has some amazing features that make it the best migration tool for Office 365.

  • Migrates from one Office 365 tenant to another without any hassles
  • Allow migration of multiple mailboxes from one tenant to another
  • Migrate unlimited user mailboxes with a CSV file
  • Offer specific filters to migrate selective data
  • Save migration report in CSV format after complete migration

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Let’s have a look at the working process of this tool:

  1. After installation, launch software on your system.
  2. From the home screen, click Add Source to add first tenant Office 365 account as the source.
    launch software on your system
  3. The Office 365/Exchange window appears on the screen, enter the Office 365 account details, and select List all mailboxes using above credentials. Now, hit the Get User mailboxes button. All the Office 365 mailboxes will appear in the tab, select the specific mailboxes, and then click Add.
    enter the Office 365 account
  4. Once mailboxes are added to the source section, click Add in the Add Destination section to add another Office 365 tenant as the destination.
    added to the source section
  5. Just as with the source section, provide credentials in the destination section for Office 365 account. Make sure you add all the mailboxes for accurate migration.
    provide credentials in the destination section for Office 365 account
  6. After adding both the source and destination mailboxes, map mailboxes to each other and then click Set Filter and Migrate.
    map mailboxes to each other
  7. In the next step, select the type of destination (Mailbox, Public Folder, Archive Mailbox) and click Migrate.
    select the type of destination
  8. The Filter Selection window will pop up on the screen; apply filters to the mailboxes if you want to, and click I am OK Start Migration.
    Filter Selection window will pop up
  9. The tool will start migrating mailboxes from one tenant to another. Once the migration is done, a notification will appear on your screen confirming the same, click OK to finish the process.
    tool will start migrating mailboxes

The migration report can be saved in a CSV format. This way, you can quickly perform Office 365 tenant to tenant migration using Office 365 Migration tool.

Manual methods Vs. Kernel Office 365 Migration Tool


Manual Methods

Office 365 Migration

Migrates mailboxes Yes Yes
Migrates archive mailboxes Yes Yes
Migrates public folder data Yes Yes
Supports batch migration Yes Yes
Migration possible from any version of Exchange Yes Yes
Easy to set up the environment No Yes
Easy migration No Yes
Can be done by non-technical users No Yes
Is reliable and secure No Yes
A similar procedure for all migrations No Yes
Fast and accurate No Yes
Offers easy selective migration of data No Yes


The manual approach of moving mailboxes from one Office 365 tenant to another is very complicated, as it is based on PowerShell scripts. Not every user is capable of using the Shell Scripts because it requires technical expertise. So, Kernel Office 365 Migration is the best option that allows you to move Office 365 mailboxes from one tenant to another. Even non-technical users can easily migrate their Office 365 data using this tool.

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