How To Seamlessly Perform A Cross-Tenant
Migration In Office 365


The process of cross-tenant migration within Office 365 is essential for organizations undergoing mergers, acquisitions, or restructuring. This task entails transferring data and services—including email, OneDrive, Teams, and SharePoint—from one Office 365 tenant to another. To achieve a successful migration, it is imperative to engage in thorough planning, utilize the right tools, and execute the process with expertise. This guide offers a comprehensive framework for facilitating an efficient cross-tenant migration.


Understanding Cross-Tenant Migration


Cross-tenant migration refers to the process of relocating users, mailboxes, domains, and associated data from one Microsoft 365 tenant to a different one. This procedure is more complex than standard migrations, as it necessitates the management of domain verifications, permission assignments, and service configurations.


Steps to Perform a Seamless Cross-Tenant Migration


1. Pre-Migration Assessment

Prior to commencing the migration process, it is essential to perform a comprehensive evaluation of both the source and destination tenants. This phase includes:

  • Inventory Analysis: Catalog and record all mailboxes, shared mailboxes, groups, OneDrive accounts, and any additional resources that require migration.

  • Licensing Requirements: Verify that the designated tenant possesses an adequate number of licenses to support all users and resources effectively.

  • Compatibility Check: Verify that the applications, integrations, and external tools are suitable for use with the intended tenant.

  • Compliance Review: Assess the data compliance obligations, including GDPR and HIPAA, to guarantee conformity throughout the migration process.


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2. Planning and Strategy Development

Develop a comprehensive migration strategy that specifies the extent of the project, the schedule, and the roles assigned. Please take into account the following aspects:

  • Migration Scope: Identify the specific data, configurations, and settings that are set to be transferred, including but not limited to emails, calendars, contacts, and shared documents.

  • Prioritization: Establish a prioritized sequence for migrating essential data and users to reduce potential disruptions.

  • Communication Plan: Communicate the migration schedule and anticipated outcomes to all relevant parties, including staff members, IT departments, and management.

  • Contingency Plans: Establish a contingency plan for backups and rollbacks to address unforeseen challenges.

3. Set Up Permissions and Prepare Tenants

Grant the necessary permissions and configure the source and target tenants to enable data transfer:

  • Enable Cross-Tenant Collaboration: Adjust the settings within Azure Active Directory (AAD) to facilitate collaborative efforts between the tenants.

  • Assign Roles: Verify that administrative accounts possess the necessary permissions to utilize migration tools effectively.
  • Prepare Users: Revise user profiles to confirm that email addresses, aliases, and permissions are aligned with the configurations of the designated tenant.

  • DNS Configuration: Revise the DNS records, including MX and Autodiscover, to ensure that traffic is directed towards the intended tenant.

4. Choose the Right Migration Tool

Selecting the appropriate migration tool is crucial for a seamless transition. Popular tools include:

  • Microsoft’s Native Tool: Well-suited for fundamental migrations, though it lacks advanced features.

  • Third-Party Tools: Platforms such as BitTitan MigrationWiz and Quest On Demand provide capabilities including mass migration, the ability to schedule tasks, and comprehensive reporting options.

5. Pilot Migration

Before migrating all data, conduct a pilot migration with a small group of users:

  • Test Workflows: Assess the migration procedure to ensure proper functioning of email services, shared resources, and access permissions.

  • Identify Issues: Identify and resolve any possible issues, including data formatting discrepancies or insufficient permissions, prior to expanding operations.

  • User Feedback: Gather input from initial users to enhance the procedure.


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6. Full Migration Execution

Execute the migration in phases to reduce the risk of downtime:

  • Mailbox Migration: Migrate emails, calendar entries, and contact information to the designated tenant.

  • File Migration: Transfer data from OneDrive, SharePoint, and Teams while preserving the existing folder structures and access permissions.

  • Update DNS Records: Update the MX records and Autodiscover records to direct them to the intended tenant, guaranteeing uninterrupted email functionality.

  • Resource Mapping: Ensure that the mapping of shared mailboxes, distribution groups, and permissions is accurately reflected in the target tenant.

Tips for a Successful Migration


  • Plan Thoroughly: A comprehensive migration strategy is essential to prevent unforeseen issues.

  • Communicate Early: Notify users regarding the timeline for migration and the anticipated modifications.

  • Leverage Automation: Leverage automated solutions to minimize manual labor and mitigate the risk of errors.

  • Test Extensively: Conducting pilot tests guarantees the dependability and effectiveness of the migration process.

  • Engage Experts: Engage IT experts or consultants who possess experience in managing cross-tenant migrations. Head over to this page for more information.