There may be times when you need to complete a mailbox migration between office 365 tenants and need to take your domain with you, for example, a company buyout.

This means you will need to decommission the domain on the current tenant and move it to another.

The process below gives you steps on how to achieve this goal. Increase licenses in Target Office 365 tenant to accommodate all mailboxes that will be migrated from the source tenant. Create Administrator accounts in source and target tenants for use in migrating from Office 365 to another Office 365. The target tenant is the Contoso Office 365 tenant to which you are migrating.