Migrating mailboxes between Microsoft 365 tenants can be a challenging yet important task, especially during mergers, acquisitions, or company rebranding. The process involves transferring emails, contacts, calendars, and other mailbox data from one tenant to another. To ensure a smooth tenant to tenant migration, careful planning is essential. This includes preparing the domains, setting up both source and target tenants properly, and verifying permissions. You can use Microsoft’s native cross-tenant migration tools or third-party solutions to automate the process.

Key factors to consider are choosing the right migration strategy—whether it’s cutover or staged—based on the number of mailboxes and the organisation’s size. Managing user identities and licenses effectively is also crucial to avoid any disruption.