MS Office 365 Tenant-to-Tenant Migration Step-by-Step Solution

Let’s proceed further and start this article with a brief introduction to migrate tenant-to-tenant Office 365.

Brief Introduction About Office 365 Tenant-to-Tenant Migration

A Tenant in Microsoft 365 refers to a particular Office 365 service environment. Where organizational data is stored, this all-inclusive ecosystem houses various organizational data, including Office 365 Mailboxes, documents, SharePoint Sites, file data in OneDrive, Teams, and more. A tenant administrator can utilize every function included within their subscription.

When a business merges, the necessity arises to relocate mailboxes to another tenant. This migration process is a challenging progression. It involves several prerequisite requirements, license acquisition, and preliminary actions. In this blog, today we will examine the principles of mailbox migrations between Microsoft 365 tenants and the planning process for this migration.

Key Reasons for Tenant-to-Tenant Mailbox Migration

There are multiple reasons why an organization performs a tenant-to-tenant migration in Office 365. Let’s discuss some of the most common ones below:-

• In the case of Merger and Acquisitions (MA) Activity:- When two or more companies merge or one company acquires another one, combining Office 365 tenants to have a single and unified environment for better management becomes essential.
• In Rebranding:- Another need could be the rebranding process. Users are required to change the company’s name or domain. Making it essential to move its data to a new tenant with a different name or domain.
• In consolidation:- When companies have multiple Office 365 tenants, managing everything can be difficult. Hence, it requires performing O365 tenant-to-tenant migration to simplify management and reduce costs.
• When a business expands:- When it grows, it requires more resources and scalability in every aspect, including Office 365. Hence, they have to migrate their data to an upgraded subscription plan to upgrade their subscription.
• Cost efficiency: The user can move its data to new tenants to reduce costs associated with licensing, support, and other related services.

Manual Procedure to Perform Microsoft 365 Tenant-to-Tenant Mailbox Migration

Office 365 tenant-to-tenant migration can provide multiple challenges depending on the specific migration scenario. Such as it typically occurs during business acquisitions, mergers, or divestitures, leading to various migration patterns, including one-time migrations, phased migrations, or split flow/tenant moves.

Manually, these migration processes are done using PowerShell scripts and professionally using third-party tools. But there is an Office 365 Pre- and Post-Migration Checklist that you should follow.

A. Pre- Migration Phase

The pre-migration phase is comprised of a four-step process. Each step has been elaborated below, such as:-

Step 01: Domain Preparation

Depending on your migration plan, consider several factors before domain preparation. General scenarios are:-

• Comprises rebranding
• Not a rebranding
• Only a cloud tenant move

Proceed with the following steps to prepare the domain based on your requirements:

• Ensures that users have enough licenses for the target Microsoft 365.
• Further, Create admin accounts in both the source and target to perform migration smoothly.
• In the target, create user mailboxes, room/resource mailboxes, and distribution groups.
• If required, perform AD DS consolidation using AD DS tools and sync the source domain with the target domain manually or by using synchronization.
• Also, train your end users regarding the post-migration use of Microsoft 365.

Step 02: Online Domain Verification

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

Verify that just one tenant is using the domain. Otherwise, the verification will fail.

As soon as these steps are done, the change will take around 72 hours to be seen.

Step 03: Scheduling Tenent Migration

• Make a list of user mailboxes that need to be migrated and create a CSV file for mapping.
• Take note of 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 at least 24 hours to complete the disabling process.

Step 04: Stages of Migration

In this fourth step, we have explained the stages of migration, which are as follows:-

1. Stop the inbound mail flow

To stop 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 important to consider 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.

2. Preparation of the Source Tenant

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

• Reset the default email address to Microsoft 365’s original email address.
• By using the Lync Admin Portal, remove all of the source tenants’ Lync licenses.
• Reset the default email address of distribution lists, rooms, and resources to the original domain.
• Delete all the secondary email addresses from all tenant objects.
• Use the Get-MsolUser -DomainName xyz.com command in Windows PowerShell to retrieve all the objects that are still using their primary email address or are refusing the removal.

3. Preparation of the target domain

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

• Set the auto-dicover CNAME.
• You must have configured a new domain in the target tenant for AD FS when using it.
• Assign licenses and activate the new user accounts in the target domain.
• On the new users, set the source domain as the primary email address (done by using Windows PowerShell). Also, decide on communicating the passwords to end-users.
• When the user mailboxes are operational, change the mail routing and point the MX record to the new Office 365 email address.
• Examine the mail flow in and out of the target tenant.

B. Initiate the Migration

• It is suggested to perform separate migrations for email, calendar, and contacts to the destination tenant mailbox when working with 500 users or less. You can apply criteria-based limitations when it comes to email migration, like migrating emails up to a certain date.
• Using the multi-pass method to migrate the contents in multiple batches when working with 500 users or more is recommended. This approach allows you to transfer contacts, calendars, and a single week’s worth of data in each pass.

Nowadays, choosing the best migration strategy and defining the type and quality of data to migrate is challenging. Although the PowerShell scripts method can be used to accomplish migration, it is difficult to note that even for Exchange professionals, this approach can be extremely complex. Careful planning is important to ensure you don’t make mistakes in executing cmdlets or steps. Additionally, it can be time-consuming, even when multiple individuals are assigned to the task. Consequently, it is highly advised to consider a third-party Office 365 Backup Tool, as it provides comprehensive control over the migration process and offers speedy and effective automation.

Most Reliable Professional Utility for O365 Tenant-to-Tenant Migration

Office 365 Backup and Restore Tool is the most secure and reliable utility that allows you to migrate Office 365 emails to multiple file formats/email clients. This software is built with multiple built-in features. Also, it has a simple, user-friendly interface. However, this software allows you to download a free demo version, which can easily migrate 50 items per folder to check this tool’s efficiency.

Let’s proceed further and move towards the Stepwise instructions for this tool.

Stepwise Instructions to Migrate from Tenant to Tenant Office 365

1. Firstly, download, launch, and run Office 365 Backup & Restore software on your device.
2. Choose Office 365 from the drop-down list & select the Use Modern Authentication Option, then enter User I’d and press the Sign-In button.
3. Further, select the Office 365 Account and click on the “Import CSV” button to migrate various Office 365 accounts.
4. After importing Office 365 account emails, preview them. Choose the emails you want to convert to another client and hit Next.
5. Pick Office 365 from the Saves/Backup/Migrate AS option.
6. Next, select the “Use Modern Authentication” option and click the Sign-In button.
7. Now, you can select filters or features as required, like Removing Duplicate Emails, Date Filters, Free Server Space, and more.
8. After selection, click the Next button, then select the Office 365 I’d in which you are converting emails.
9. Then, select the Mailbox/Public Folder/Online archive option where you want to convert emails per your requirement.
10. After selecting, hit the Convert button to start the process.

Conclusion

This complete step-by-step guide explains a clear roadmap for migrating your Office 365 tenant-to-tenant migration. We understand that migration can be difficult, but with careful planning and execution, it can be overcome. But by following this write-up and reaching out for assistance when necessary, you can easily migrate tenant-to-tenant Office 365. However, if you want a tool to simplify and automate the migration process, consider utilizing a third-party Office 365 Backup Tool.

Frequently Asked Questions