HomeOffice 365How to Migrate Office 365 to Office 365 Account/Domain: A Step-by-Step Guide

How to Migrate Office 365 to Office 365 Account/Domain: A Step-by-Step Guide

Migrating from one Office 365 (now Microsoft 365) account or domain to another is a common scenario for organizations undergoing mergers, acquisitions, rebranding, or internal restructuring. Whether you’re moving users to a new domain within the same tenant or transferring them to a completely different tenant, proper planning and execution are critical to ensure minimal disruption and data integrity.

In this blog, we’ll explore how to migrate Office 365 to Office 365, including the difference between account-level and domain-level migrations, and a clear, step-by-step roadmap to guide you through the process.

Why Migrate Office 365 to a New Account or Domain?

Here are some typical reasons businesses perform these migrations:

  • Company mergers or acquisitions
  • Business rebranding requiring a new domain
  • Restructuring with tenant consolidation
  • Compliance or regulatory changes
  • Separation of business units or divestitures

Regardless of the reason, the migration should be seamless for users, preserving emails, contacts, files, and collaboration tools.

Understanding the Scope of Migration

There are two main types of Office 365 to Office 365 migrations:

  1. Same-Tenant Domain Migration
    • Scenario: You’re switching from oldcompany.com to newcompany.com within the same Microsoft 365 tenant.
    • Typically involves email alias and primary SMTP address changes.
  2. Tenant-to-Tenant Migration
    • Scenario: You’re moving users and data from one Office 365 tenant to another (e.g., from companyA.onmicrosoft.com to companyB.onmicrosoft.com).
    • Requires tools and more complex coordination.

This blog will focus primarily on the tenant-to-tenant migration, but we’ll briefly touch on domain changes within the same tenant as well.

Pre-Migration Checklist

Before starting, make sure you:

  • Have global admin access on both source and target tenants
  • Ensure licensing is ready on the destination tenant
  • Inventory the objects to migrate: users, mailboxes, OneDrive, Teams, SharePoint, etc.
  • Identify your migration timeline and cutover plan
  • Backup critical data
  • Notify users and prepare support materials

Step-by-Step Guide: Tenant-to-Tenant Office 365 Migration

Step 1: Prepare Source and Target Tenants

  • Set up user accounts in the target tenant (manually or via Azure AD sync)
  • Assign appropriate Microsoft 365 licenses
  • Prepare and verify the new domain in the target tenant
  • Unlink the domain from the source tenant when ready

⚠ Note: A domain can only be associated with one tenant at a time.

Step 2: Choose the Right Migration Tool

Microsoft doesn’t provide a built-in tool for full tenant-to-tenant migrations. Choose a reliable third-party tool like:

  • BitTitan MigrationWiz
  • Quest On Demand Migration
  • SkyKick
  • AvePoint Fly

These tools support the migration of:

  • Mailboxes (emails, calendars, contacts)
  • OneDrive for Business files
  • SharePoint Online content
  • Teams (chats, channels, settings)
  • Microsoft 365 Groups

Step 3: Domain Transition and DNS Changes

  • Remove the domain from the source tenant
  • Add and verify the domain in the target tenant
  • Update MX, CNAME, TXT, and other DNS records to point to the new tenant

This step typically happens during the cutover weekend to minimize email downtime.

Step 4: Data Migration

Using your chosen tool, initiate the migration of:

  • Email mailboxes
  • OneDrive user content
  • SharePoint document libraries
  • Teams configuration and data
  • Outlook rules, signatures, and contacts (if needed)

Some tools offer pre-stage migration, allowing you to move most of the data in advance and only sync changes on the final day.

Step 5: Post-Migration Validation

Once the migration is complete:

  • Verify mailbox and OneDrive access
  • Confirm all data is intact
  • Test email delivery and calendar functionality
  • Validate SharePoint and Teams settings
  • Reconnect Outlook and mobile devices to the new tenant
  • Reapply permissions and sharing settings where needed

Optional: Same-Tenant Domain Migration Steps

If you’re only changing domains within the same tenant:

  1. Add the new domain in Microsoft 365 Admin Center
  2. Verify the domain via DNS
  3. Update user email addresses to the new domain (set as primary SMTP)
  4. Update login UPNs (User Principal Names) if required
  5. Rebrand Teams, SharePoint sites, and email signatures

No data migration is needed in this case, as the content remains within the same tenant.

Best Practices for a Smooth Migration

  • Run a pilot migration with a small group before a full rollout
  • Communicate proactively with users to minimize confusion
  • Avoid peak business hours for cutover
  • Monitor migration logs for failures or delays
  • Plan for coexistence if there’s a long transition period

Conclusion

Migrating from one Office 365 account or domain to another doesn’t have to be overwhelming. With proper planning, the right tools, and a structured approach, you can ensure a smooth transition with minimal impact on productivity. Whether you’re changing tenants or just updating your domain, the key is to prepare thoroughly and test rigorously.

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