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How to Migrate Exchange Online Users Between Microsoft 365 Tenants
Question details
The user needs to move Exchange Online users, mailboxes, calendars, contacts, and a custom domain from an incorrect Microsoft 365 tenant to the correct one without utilizing an on-premises Exchange server.
- Product
- Microsoft 365
- Device & OS
- not provided
- Scenario
- Performing a cross-tenant migration of Exchange data and transferring an active custom domain to a new Microsoft 365 environment.
- Observed behavior
- Users were provisioned in the wrong tenant, but their custom domain cannot be active in both the source and target Microsoft 365 tenants simultaneously.
Verify that you have Global Administrator credentials for both the source and target Microsoft 365 tenants, and document all existing DNS records for the domain before initiating the transfer.
Perform a Cross-Tenant Domain and Mailbox Migration
This solution outlines the standard sequence to move users, migrate their Exchange mailbox data, and transfer the custom domain to the target tenant.
Because Microsoft 365 does not allow a single custom domain to exist in multiple tenants simultaneously, you must orchestrate a coordinated cutover. You will first prepare the target accounts using a default routing domain, migrate the data, and then transfer the custom domain.
Log in to the target Microsoft 365 Admin Center and create the new user accounts. Temporarily assign them the default '.onmicrosoft.com' domain associated with the target tenant.
Use the built-in Microsoft 365 cross-tenant mailbox migration features, or a third-party migration tool, to copy all emails, calendars, and contacts from the source accounts to the newly provisioned target accounts.
In the source tenant's Microsoft 365 Admin Center, remove the custom domain from all user aliases, groups, and resource accounts. Once all dependencies are cleared, delete the custom domain from the source tenant.
Switch to the target tenant's Admin Center, navigate to Settings > Domains, and add the custom domain. Follow the prompts to add the required TXT or MX record to your DNS host to verify ownership.
Configure the required MX, Autodiscover, and SPF records in your DNS host to point to the new tenant. Finally, update the target user accounts in Microsoft 365 to use the newly verified custom domain as their primary email address.
Equip Your Migrated Users with WPS Office
While you manage the complex backend migration of Microsoft 365 tenants, ensure your users have a reliable, lightweight, and cost-effective productivity suite. WPS Office is an excellent alternative for teams looking to reduce licensing costs without sacrificing capabilities.
- 1. Download the installer: Visit the official WPS Office website and click the free download button for your operating system.
- 2. Install WPS Office: Run the downloaded installation file and follow the quick setup wizard to install the software on your device.
- 3. Open migrated documents: Launch WPS Office, sign in if desired, and instantly open and edit the Word, Excel, or PowerPoint files you've migrated.
Frequently Asked Questions
Can I keep the custom domain active in both tenants during the migration?
No. Microsoft 365 strictly prohibits a custom domain from being active in more than one tenant at a time. The domain must be entirely removed from the source tenant before it can be added and verified in the target tenant.
Do I need an on-premises Exchange server to migrate mailboxes between tenants?
No, an on-premises server is not required. You can migrate mailbox data directly from cloud to cloud using native Microsoft 365 cross-tenant migration tools or specialized third-party cloud migration software.
What happens to emails sent to my domain while the transfer is taking place?
During the brief period when the domain is being removed from the source, verified in the target, and MX records are updating, incoming emails may bounce or experience delays. This is why domain cutovers are typically scheduled during low-traffic maintenance windows.
