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Summary: This content provides a detailed guide for migrating Office 365 tenants, addressing pre-migration steps, domain verification, scheduling, and migration stages. It recommends the Kernel Office 365 Migration Tool for an efficient and secure transition while comparing it favorably to manual methods.

In recent years, Office 365 has established itself as the preferred productivity platform for businesses, regardless of their scale. As businesses increasingly adopt Office 365, the demand for tenant-to-tenant migrations has grown. While Office 365 offers several built-in tools for transferring users and data, the migration process can remain intricate and time-intensive.

To streamline the Office 365 tenant-to-tenant migration process, we’ve compiled a comprehensive, step-by-step guide. This guide encompasses every aspect, spanning from initial planning and preparation to the execution phase and post-migration tasks. By adhering to these steps, you can guarantee a successful migration while minimizing disruptions to your users.

More about Office 365 tenant to tenant migration

In Microsoft 365, a ‘tenant’ refers to a distinct Office 365 service environment. It represents a particular geographic location, such as Europe or North America, where organizational data is stored. This encompassing environment houses various organization data, including Office 365 Mailboxes, Documents, SharePoint Sites, file data in OneDrive, Teams, and more. A tenant administrator possesses access to all the features provided within their subscription.

During business merger scenarios, the necessity to relocate mailboxes to another tenant arises. This migration process is not a straightforward progression; it entails several preparatory steps, prerequisite requirements, and the acquisition of licenses.”

Today, we will delve into the fundamentals of migrating mailboxes from one Microsoft 365 tenant to another. Furthermore, we will explore the planning process for this migration.

Instant Solution

For a professional and efficient migration of mailboxes, public folders, and archive mailboxes between Microsoft 365 tenants, consider utilizing the Kernel Office 365 Migration Tool.

A Simple Approach to Microsoft 365 Tenant to Tenant Migration

A Microsoft 365 tenant-to-tenant migration can pose diverse challenges contingent upon your specific migration scenario. These migrations typically occur during business acquisitions, mergers, or divestitures, leading to various migration patterns, including one-time migrations, phased migrations, or split flow/tenant moves.

The Microsoft 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

Depending on your migration pattern, you may have various considerations before domain preparation. Usual scenarios are:

  • Involves re-branding
  • No rebranding
  • Just a cloud tenant move

Based on your requirements, prepare the domain with the following steps:

  • Ensure that you have enough licenses for the target Microsoft 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 the source domain with the target domain manually or using synchronization.
  • Train your end users regarding the post-migration use of Microsoft 365.

Step 2. Domain verification

  • Start verification of target tenant domain in Microsoft 365.
  • Add a source domain in the target Microsoft 365 admin center and create TXT records in DNS.

Make sure the domain is in use with 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 the MX record (of the primary email domain).
  • Disable directory sync for source tenant (from Microsoft 365 admin center) to avoid sync of any modifications in source tenant account AD DS to Microsoft 365 platform. It can take a minimum of 24 hours to complete the disabling process.

Step 4. Migration Stage

  • Stop inbound mail flow

    To halt inbound mail flow to the source tenant, you can achieve this by altering the primary MX record to an unreachable value or by employing a third-party service. It’s essential to take into account the shortest Time to Live (TTL) value on the MX record (for the primary email domain) that you identified during your preparation phase. This will enable you to plan the timing of this step effectively.

  • 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 Microsoft 365.
    • Remove all the Lync licenses from the source tenant with the help of the Lync Admin Portal.
    • Reset the default email address of distribution lists, rooms, and resources to the initial domain.
    • Remove the secondary email address from all tenant objects.
    • In 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 (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 the 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 dealing with 500 users or fewer, it is advisable to perform separate migrations for email, calendar, and contacts to the destination tenant mailbox. In the case of email migration, you can implement criteria-based limitations, such as migrating emails up to a certain date.
  • When dealing with 500 users or more, it is recommended to employ the multi-pass method to migrate the contents in multiple batches. This approach allows you to migrate contacts, calendars, and a single week’s worth of data in each pass.

Now, it’s crucial to determine the migration method, including specifying the type and quantity of data to be migrated. While it’s possible to perform migrations using PowerShell scripts, it’s important to note that this method can be exceedingly intricate, even for Exchange experts. It demands meticulous preparation to ensure that you avoid errors in executing cmdlets or steps. Additionally, it can be time-consuming, even when multiple individuals are assigned to the task. Consequently, it is highly recommended to consider third-party migration tools, as they provide comprehensive control over the migration process and offer rapid and efficient automation.

What Experts Think About Kernel Office 365 Migration Tool?

When undertaking an Office 365 tenant-to-tenant migration, safeguarding your data is of utmost importance. Many migration experts strongly advocate the use of a dependable and secure migration tool for Microsoft 365 tenant-to-tenant migration, as it guarantees the safe transfer of your data without any corruption. Furthermore, these tools ensure that your data retains its original structure and format even after the migration is complete. They automate the migration process, reducing the need for extensive manual intervention. This allows administrators to focus on other tasks concurrently while the migration progresses.

Kernel Office 365 Migration tool – For a quick and easy O365 tenant to tenant migration

Kernel Office 365 Migration is an advanced tool specifically tailored for Office 365 tenant-to-tenant migrations. It offers users a seamless way to migrate all Microsoft 365 mailboxes from one tenant to another. With a range of exceptional features, it stands out as the premier migration tool for Microsoft 365.

  • Migrates from one Microsoft 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

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 the first tenant Microsoft 365 account as the source. launch software on your system
    Note: You can use Basic Authentication or Modern Authentication as per your requirements.
  3. The Office 365/Exchange window appears on the screen, enter the Microsoft 365 account details, and select List all mailboxes using above credentials. Now, hit the Get User mailboxes button. All the Microsoft 365 mailboxes will appear in the tab, select the specific mailboxes, and then click Add.
    enter the Microsoft 365 account
  4. Once mailboxes are added to the source section, click Add in the Add Destination section to add another Microsoft 365 tenant as the destination.
    added to the source section
    Note: Here also, you can use Basic Authentication or Modern Authentication as per your requirements.
  5. Just as with the source section, provide credentials in the destination section for your Microsoft 365 account. Make sure you add all the mailboxes for accurate migration.
    provide credentials in the destination section for Microsoft 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 Microsoft/Office 365 tenant to tenant migration using the third-party 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 is 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


In this comprehensive step-by-step guide, we have provided a clear roadmap for migrating your Office 365 tenant to a new one. We understand that migrations can be complex, but with careful planning and execution, they can be manageable. By following these outlined steps and reaching out for assistance when necessary, you can successfully transition your organization to a new Office 365 tenant.

However, if you’re seeking a tool to simplify and automate the migration process, consider utilizing Kernel’s Office 365 Migration tool. The best part? It’s available free of charge, making it a compelling option to explore. Don’t hesitate to get started today. This tool supports all Office 365 (Microsoft 365) plans, including GCC High, GCC, DOD, and Commercial Microsoft 365 plans.


Frequently Asked Questions

However, if you’re seeking a tool to simplify and automate the migration process, consider utilizing Kernel’s Office 365 Migration tool. The best part? It’s available free of charge, making it a compelling option to explore. Don’t hesitate to get started today. This tool supports all Office 365 (Microsoft 365) plans, including GCC High, GCC, DOD, and Commercial Microsoft 365 plans.

Q- Why does one require to move content from one Microsoft 365 tenant to another?

A- Microsoft 365 tenant to tenant migration depends on multiple business scenarios such as business mergers, acquisitions, business data migration projects, re-branding, etc.

Q- Why is domain verification crucial in the manual tenant migration process?

A- For the migration process, it is vital to have a domain attached to a single domain, either source or destination at a time. So, source domain data need to be transferred to the destination account before detaching it from the source account. Then, attach the domain to the destination account and finally detach from the source account. For all these processes. This source domain in the destination account needs to be verified for authentication via TXT records in DNS for authentication purposes.

Q- What are the limitations of the manual Microsoft 365 tenant to tenant migration?

A- Hardly, there is any manual process to migrate a Microsoft 365 tenant to another which is a complex process of using PowerShell scripts, and limits of 500 mailboxes migration is another challenge that needs to be completed by using a smart and robust Microsoft 365 Migration tool.

Q- How can one take benefits of the professional Office 365 Migration tool?

A- A reliable professional Microsoft 365 migration tool like Kernel Office 365 Migration tool offers many advantages to its users by facilitating quick migrations, intelligent filters, unlimited data migration, all sorts of content from mailboxes, groups, public folders, tenants migration with support to all plans and Windows OS versions without compromising the original structure and properties.

Q- How can I connect Windows PowerShell to Exchange Online manually?

A- To run cmdlets in Exchange Online PowerShell for performing data migration, you need to connect Windows PowerShell to Exchange Online, i.e. configuring Exchange Online account in the PowerShell application.

Kernel Office 365 Migration