Moving mailboxes, OneDrive, domains and devices from one Microsoft 365 tenant to another, or merging several tenants into one after a rebrand or an acquisition. Done hands-on by the consultant who has moved three organisations between tenants this year, with a cutover runbook and hypercare after go-live.
Not every project needs a migration. If one site or business unit simply needs to run its own users and devices, administrative segregation inside the shared tenant is often the better answer.
Tenant-to-tenant and cross-tenant mailbox and OneDrive moves, run as MigrationWiz projects. Data is pre-staged ahead of time, so cutover moves only what has changed.
After a rebrand or an acquisition, two or three tenants become one: one directory, one set of policies and one licence position to reconcile.
The alternative to splitting. A business unit manages its own users, mailboxes and devices inside a shared tenant, with no rights over anyone else.
A domain can only be verified in one tenant at a time, so the move is sequenced, timed and written down beforehand.
File servers and old shares moved into SharePoint with a structure and permissions that make sense.
Devices tied to the old tenant are brought into the new one, so they land managed and compliant, not orphaned.
OneDrive sizing. Mailboxes rarely set the timetable; a handful of very large OneDrives do. Guest accounts. People who already exist in the target tenant as guests collide with the accounts being created for them. Licence mismatches. The target needs the right licence assigned before there is a mailbox or OneDrive to migrate into. Service accounts. The migration account is blocked by a forgotten Conditional Access policy.
Each of these is found in discovery, not on cutover night.
Migration is one part of our wider infrastructure and security work. The hotel group example is written up in the case studies. If the new tenant has to pass an assessment, see Cyber Essentials readiness; if the network is changing at the same time, see network security and Fortinet.
Mailboxes, OneDrive sizes, domains, devices, guests, licences and service accounts inventoried. Then the decision: migrate, consolidate or segregate.
The target tenant is built and licensed, MigrationWiz projects are set up, and the bulk of the data is copied while people carry on working in the source.
A written runbook with timings, owners and a rollback point: final delta sync, domain moved, DNS switched, devices re-enrolled.
On hand after go-live for profiles, permissions and stragglers, with a handover document and a user guide.
Further reading — Related guides: Microsoft 365 tenant-to-tenant migration: a practical guide and delegating admin safely in a shared tenant.
Book a free discovery call. Bring the mailbox count, the domains and your target date. You will get a straight view of whether to migrate, consolidate or segregate — no obligation.