How to Move a Microsoft 365 Domain Between Tenants and Preserve Email

Navigate to the Microsoft 365 Admin Center of the destination tenant. Pre-create the user accounts, prepare the necessary Microsoft 365 licenses, and set up target SharePoint sites to receive the data.

In the source tenant's Admin Center, navigate to Settings > Domains. Reassign all user aliases, groups, and resources away from the custom domain to the default '.onmicrosoft.com' domain. Once all dependencies are cleared, select the custom domain and click 'Remove domain'.

Log into the destination tenant's Admin Center, go to Settings > Domains, and click 'Add domain'. Enter your custom domain name and update your DNS host provider records to verify domain ownership in the new tenant.

In the Exchange Admin Center, assign the newly verified custom domain email addresses as the primary SMTP address for your users. This ensures the correct address displays in Microsoft Teams. Finally, test mail flow, sign-in capabilities, and file access.

Choose a trusted third-party migration tool. Authorize the application to access both your source and destination Microsoft 365 tenants using Global Administrator credentials.

Map the source user accounts to the destination user accounts within the tool. Run a pre-stage migration to copy the bulk of the email and file data in the background without affecting end users.

Remove the domain from the source tenant and add it to the target tenant as described in the manual process. Run a final delta sync in your migration tool to capture any remaining emails or files delivered during the cutover window.