Office 365 To Office 365 Migration: How To Move
Email And Data Without Disruption


In the rapidly evolving digital work environment, companies frequently find it necessary to reorganize, merge, or restructure their Microsoft 365 (previously known as Office 365) tenants. This need often arises from mergers, acquisitions, or changes in organizational structure, making the migration between Office 365 tenants a common occurrence. 

This guide provides an overview of the key components involved in migrating from one Office 365 tenant to another, outlines recommended practices to follow, and details how to facilitate a smooth transition for emails, calendars, OneDrive, SharePoint, Teams, and other services. Discover more by clicking this source.


Understanding Office 365 to Office 365 Migration


What Is Tenant-to-Tenant Migration?

Migrating from one Office 365 tenant to another entails transferring various types of data—including email accounts, documents, and collaborative content—from one Microsoft 365 organization to a different one. Such migrations typically take place in scenarios like:

  • Mergers and acquisitions

  • Rebranding or organizational restructuring

  • Compliance with legal mandates

  • Divestitures and spin-offs

Since each tenant operates independently, Microsoft does not offer native tools for direct tenant-to-tenant migration. 


Planning for a Smooth Office 365 Migration


Assess and Inventory Your Environment

Before starting the migration process, conduct a comprehensive evaluation of both the source and destination tenants. Take stock of the user count, data volume, mailboxes, shared mailboxes, distribution lists, OneDrive files, SharePoint sites, Teams channels, and associated permissions.


Choose the Right Time and Minimize Downtime

One of the primary objectives of any migration is to reduce the impact on business operations. Choose a migration timeframe that will result in minimal disruption, typically during weekends or outside of regular business hours. Make sure to notify stakeholders and have user communications ready beforehand.



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Use a Pre-Migration Checklist

Before migration, it is essential to have a checklist that consists of the following items:

  • Verify the licensing for the destination tenant

  • Establish DNS records

  • Ready both the source and destination environments

  • Set up global administrator permissions

  • Activate mailbox auditing and logging

  • Inform end-users about the process

Migrating Mailboxes and Email Data


Email Migration Options

There are multiple methods for migrating email data:

  • Manual Export/Import: This involves exporting PST files from the source and importing them into the destination tenant, but it may not be practical for larger organizations due to scalability issues.

  • PowerShell Scripts: These scripts are beneficial for smaller, more technically proficient migrations.

  • Third-Party Migration Tools: Solutions such as BitTitan, Quest, or Cloudiway can streamline and automate the mailbox migration process, ensuring that folder organization, read/unread statuses, calendar invitations, and more are maintained.

Key Email Components to Migrate

  • Main email accounts

  • Archived email accounts

  • Schedules and event invitations

  • Address books

  • Email filters and signatures

  • Collaborative email accounts

Avoiding Email Downtime

To reduce interruptions during the email migration process:

  • Conduct the migration in small batches for gradual transfer

  • Set up temporary mail forwarding

  • Pre-synchronize calendars and mailbox content before switching the MX records

  • Check the MX and Autodiscover DNS settings on the new tenant to ensure they are correct.


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Migrating OneDrive, SharePoint, and Teams Data


OneDrive and SharePoint Migration

Transferring content from OneDrive and SharePoint requires the relocation of user files, access permissions, and document libraries. Utilizing tools such as ShareGate, Microsoft’s SharePoint Migration Tool, or various third-party solutions can assist in duplicating structures and preserving access rights.


Teams Migration

For a Teams migration to be successful, it is essential to move not just the Teams and channels but also conversations and chat history, shared files, meeting recordings, and tabs. To guarantee that this information is accurately retained and continues to work properly after the migration, it is advisable to utilize dedicated migration tools.


Post-Migration Best Practices


Validate Data Integrity

After the migration is finished, it is crucial to ensure data integrity by rigorously testing several mailboxes and shared folders. This includes confirming user access to OneDrive and SharePoint, assessing the performance of Microsoft Teams—including chat history—and generating detailed reports to detect any issues or absent data across the entire system.


Communicate and Train Users

Offer users instructional materials or quick-start resources to help them navigate their new environment. Establish helpdesk assistance for any issues that arise after migration. Frequently encountered problems may involve lost contacts, calendar discrepancies, or malfunctioning links.


Decommission the Old Tenant (If Applicable)

Once you have confirmed that the data migration is complete and the system is stable, proceed to deactivate the old tenant only if there are no legal or compliance obligations to keep it. Make sure to record all actions for auditing and governance needs.