Treat the tenant as an operating platform
A Microsoft 365 migration is not just an Exchange move. The target tenant becomes an identity, collaboration, device-management and security platform. Define naming, administration boundaries, emergency access, authentication methods and ownership before bulk migration begins so migration tooling does not set the long-term design by accident.
Resolve identity and domain decisions early
Document authoritative identity sources, Entra ID synchronisation, guest access, accepted domains and UPN changes. Domain verification and DNS changes need controlled sequencing, particularly when mail routing, third-party security gateways or coexistence are involved.
Build security into the target state
Establish MFA, Conditional Access, privileged administration, Defender controls and audit retention before users arrive. A migration window should not become a period where a newly created tenant operates with weaker controls than the environment it replaces.
Test the user journey, not only data transfer
Pilot sign-in, Outlook profiles, mobile access, Teams, OneDrive, shared resources and line-of-business integrations. Migration success means people can work securely after cutover, not simply that a migration tool reports completed objects.
AL Group can assess, design, implement and operate the underlying technology rather than stopping at advice.
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