How to Switch Microsoft 365 Tenant | A Scenario-Based Guide

Katherine Casey — Thu, 23 Apr 2026 12:40:00 +0000

The process to switch tenants in Microsoft 365 may look simple if you’re not involved in it. In reality, the scene is quite different. When you see it through a real-world scenario, the process becomes much easier to understand and plan.
Imagine a startup that was growing exponentially, announced a merger with another firm. Both were using Microsoft 365, but under different tenants. Now, the IT team had one clear goal: switch the Microsoft 365 tenant with zero disrupting emails, files, or collaboration. The challenge wasn’t just technical. It was just more than operational.

Understand the Situation: Two Tenants, One Unified Workspace

Both growing startups and the well-established firm had their separate Microsoft 365 domains, user accounts, along with data stored across Exchange, OneDrive, & SharePoint. To unify their operations, they needed a complete Office 365 tenant-to-tenant migration that would merge all users and data into a single & sleek environment.

The First Concern Comes to Mind: “Will We Lose Our Data?”

Every organization & individuals that plan for Office 365 tenant-to-tenant migration has a primary concern: data safety. No one wants to lose their emails, files, & shared content, so employees immediately started worrying. The IT team understood that during any M365 tenant-to-tenant migration, data safety, folder structures, permissions, & overall data integrity with metadata prime is necessary, which is absolutely critical to avoid business disruption.

The Initial Plan They Followed: Manual Migration

At first, the IT team considered manual methods to migrate Microsoft 365 tenants. However, the process was technical and needed more planning from pre-migration to post-migration) for execution. Apart from that, the team went through the following stages and their steps:

Stage 1: Assessed and Prepared Tenant Accounts

At the very first, the team identified the source and target tenant accounts and did a complete inventory of both accounts.
Next, they listed all the users, mailboxes, domains, and their Exchange Online licenses in one place.
After that, they examined the existing custom domain and subscription of the Office 365 account.
In the next steps, they verified the litigation hold, compliance policies, & retention controls.
Moreover, the process to lower the DNS TTL value was completed 24-48 hrs before starting the migration.
Once all that was done, they removed the custom domain from the source Microsoft tenant account.
Then, added and verified the domain in the target tenant account.

Stage 2: Configuring Cross-Tenant Relationships

After accessing and preparing tenants, the IT team followed the steps below to establish trust as well as relationships between Microsoft tenants:

Next, the IT team moved External Identities within the O365 Azure AD account.
Configured the cross-tenant settings and allowed B2B collaboration.
Established the relationships within Exchange Online PowerShell.
Then, the team allowed the permissions for mailbox replication. _This is the complete pre-migration stage along with steps that the IT team follows for the M365 tenant-to-tenant migration.

Stage 3: Created Migration Endpoints and Mapped Mailboxes

After pre-migration preparation, the IT team used Exchange Online PowerShell to create migration endpoints.
Provided authentication to the endpoints with global admin credentials and validated their connectivity.
Then, in the Exchange Admin Center, choose the Create Migration Batches option from the Migration.
Made the new batches for migration, assigned them a name, assigned endpoints, and mapped the mailboxes.
After creating a CSV for mailbox mapping.
Once all was done, they clicked on Start Migration to begin the process. _When the migration started, they continuously expanded the real-time migration progress.

The Challenges They Faced During Migration

As the process began after following such complex steps, issues started appearing, data mismatches, broken permissions, excessive time consumption, etc. They faced downtime and difficulties when managing bulk users and mailboxes.

The Smarter Shift: Adopting an Advanced Cloud Tenant Migration Way

After realizing the risks associated with manual methods, the team decided to use a professional, dedicated cloud tenant migration medium. This approach automated the process, reduced manual effort & guarantees the accurate migration of all data between tenants.

The Final Result: Effective Migration

After the migration via automated medium of migration, employees logged in and continued working as usual; emails were intact, and files were accessible. Even collaboration remained uninterrupted after the merger. A well-planned Office 365 tenant-to-tenant migration made the entire transition almost invisible to end users.
The final learning of this scenario is that the switching of Office 365 tenants is not just about moving data; it’s about maintaining continuity.

DEV Community: Katherine Casey