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How to Migrate Mailboxes from One Microsoft 365 Tenant to Another? Complete Guide

Mohit Jha ~ Modified: March 2, 2022 ~ 8 Minutes Reading

Summary: This comprehensive article outlines all of the necessary steps for a successful data transfer in Office 365. To migrate mailboxes from one tenant to another without errors or data loss, read and follow each step described below.

There are various conditions, where the need for data migration arises within the business organizations. It might be a merger, acquisition, or rebranding, etc. however, there is no manual solution that can completely migrate these data from source to destination.

Microsoft still suggests third-party migration software, when it comes to migrating office 365 from one tenant to another. Therefore, in the coming section, we are going to discuss the initial steps, premigration preparation, domain verification, and other important steps and checklist in detail, to avoid any error in the data migration process.

Instant Solution: If you do not want to go through the hassles of manual methods, you should choose the Most Dependable & Secure Office 365 to Office 365 Migration Software. The software is created to make the data transfer as simple as possible for novice users.

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Initial Steps That You Need to Take:

In the very first step, you need to create the source users, groups, and all other objects in the destination tenant manually. You can use the PowerShell scripts or through Active Directory Domain Services (AD DS) consolidation to merge into the destination tenant.

Once, you have done the initial steps by creating all user’s accounts and groups in the destination tenant. Now, you can modify the user’s UPN based on your requirement.

It’s Always a Good Approach to Plan Two weeks Before You Migrate

Migrating all the organization data is massive activity to perform. We should ensure all the best practices and approaches for the same.

It’s always the best idea to prepare a comprehensive plan before two weeks to avoid the last-minute rush. Let’s discuss a few important checklists for the same.

Client Considerations is Crucial Before Moving Email Domain from One Office 365 Tenant to Another

If any of these tenants, using Outlook 2010 or above, then you must remove the Outlook user profile and need to create it again.

If you are using Outlook 2007 and Outlook 2010, then when you will be restarting the client, auto-discover will configure the client and rebuild the .OST file.

Hence, ensure these checklists before proceeding any further.

Also Read: Comprehensive Guide to Copy Files from One Channel to Another in Microsoft Teams

Ensure Tenant Preparation and Licensing

As we are migrating mailboxes from one tenant to another, then there might be scenarios, where you need to increase user licenses in the destination tenant.

Also, ensure that destination user accounts has enough storage space and respective licenses to accommodate all mailboxes that will be migrated from the source tenant.

You will require an admin account of both source and destination while performing the migration in Microsoft 365.

Create Users, Distribution Groups, and Other Object in the Target Tenant

Read the below instructions in order to create the resources in the destination tenant:

You must need to create the source users, groups, and all other objects in the destination tenant manually if you are using the Azure AD Connect tool. You can use the PowerShell scripts or through Active Directory Domain Services (AD DS) consolidation to merge into the destination tenant.

This operation can be done via various AD DS tools. Moreover, this task can take extra time and planning depending on the number of objects and users that need to be moved. Therefore, it should be completed before the migration project.

Now ensure that all the new users and groups are synced to the destination tenant using directory synchronization.

Must Read: How to Move Files Between OneDrive For Business Accounts – Easy & Ultimate Solution

Proper End-user Communications

Now, you should make a communication plan and start informing users of the upcoming migration and service changes.

Also, make sure to guide users on how to connect to Outlook on the web along with their new sign-on credentials, just in case they have a problem after migration.

Important Preparation & Pre-migration Activities: Three Days Before You Migrate Office 365 from One Tenant to Another

Now follow these important steps before the data transfer operation:

Domain Preparation

Here, you need to begin the domain verification process on the destination tenant for the source email domain.

Then, in the destination tenant go to Microsoft 365 admin center, and add the source domain and create TXT records for the same, in Domain Name Systems (DNS) for respective verification. This process can take plenty of time and up to 72 hours to reflect.

Migration Scheduling

In this step, you need to create a list of user’s mailboxes that you want to transfer from source to destination.

For this step, you can create a CSV file that later will use by the migration tool in order to create a mapping.

Mail Exchanger Record (MX record) Time to Live (TTL) Test

Now, you have to schedule the TTL test. In order to accomplish this task, you need to change the TTL value in the DNS setting while browsing to MX record for the primary email domain you wish to transfer to a small number (i.e. 5 minutes).

Make sure it needs to be changed 4 hours before your migration begins. You can verify these settings and changes in MX lookup.

Disable Directory Sync in Source Tenant

This is the last and most important step before migrating office 365 from one tenant to another. Go to the source tenant O365 admin center, here, you need to disable directory sync.

It can take up to 24 hours to reflect the changes and hence, need to be done before the migration. Once, you have done the same, from now onwards any changes in the source Office 365 tenant AD DS will no longer sync to the Office 365 organization. Now we are all set to move towards the migration process.

Top-Rated Software on How to Move Office 365 from One Tenant to Another

Now after ensuring all the above checklists and steps, it’s time to perform the migration task in most secure way. In order to do that, we have to use one of the most reliable tools for this operation. We suggest you Office 365 to Office 365 Migration Tool, this is a brilliant solution, specially made for Office 365 migration operations.

It ensures maximum data security and integrity while offering a smooth data transfer experience to its users. It can easily migrate emails, contacts, calendars, tasks, and documents as well. Here are the software steps for the same.

Follow Software Steps to Migrate Mailboxes from One Tenant to Another Step by Step

Step 1. Run the software and select Office 365 as the source and destination. Check email, contact, calendar, and document checkbox to the migration process.

Step 2. The tool provides a Date-based filter, migrate document permission, use group mapping, migrate document permission. Enable the required option and click on Next.

Step 3. Now, log in to Office 365 source tenant with Admin ID and Application ID. Then, validate permissions and click on Next.

Step 4. Log in to Office 365 destination with Admin ID and Application ID, click on the validate permissions. Click Next to move email domain from one office 365 tenant to another.

Step 5. Here are three options – Fetch User, Import users, Download Template.


Step 6. Now, we have to create a mapping between source and destination users. Click on the Download template. In this CSV file, you have to mention source domain user ID and destination users ID. Then, upload it to the software.

Step 7. After that, validate the required permissions by clicking the validate button.

Step 8. Now, click on the Start Migration button to migrate mailboxes from one tenant to another.


Get a Chance to Use this Software for Free

Use the limited period free demo version of this utility. You can easily avail of themselves, by downloading the tool from the above link. Install, and sign up with your email address, and activate it. Moreover, you can use this free version to migrate two O365 user’s accounts for free.

Final Verdict

We have successfully described each step and checklists for a safe and successful data transfer in O365. Hence, users are advised to follow the same to avoid any error or complications, that may further create data loss.

Also, it is suggested to use the above-mentioned software to migrate mailboxes from one tenant to another, as it ensures maximum data protection in minimum time, and does not require any PowerShell scripts of prior technicalities.