#Cutover

1. Remove the domain from the source tenant

If you plan to move your custom domain from the old Microsoft 365 tenant to the new one, you first need to remove it from the old tenant.

1. Log in to your Microsoft 365 admin center (Office 365 admin center).

2. Go to Settings > Domains.

3. Select the domain you want to remove, and click Remove domain.

4. In the confirmation window, click Remove to confirm that you want to remove the domain.

2. Change DNS records (MX, Autodiscover)

3. Update Outlook profiles

If your Outlook cannot connect to the new tenant, you need to create a new Outlook profile for each user in your domain. Fly provides a Fly Assist tool to automatically update the Outlook profile of users to make sure the users can use the new email address after the Exchange Online migration. Refer to Configure the Outlook Profile for details.