Microsoft 365 tenant-to-tenant migrations continue to be driven by mergers, acquisitions, and restructuring, but the real complexity isn’t in the tools, it’s in the decisions you make along the way. These decisions directly impact user experience, security posture, and long-term operability of the environment.

This session is built on real-world migration projects and focuses on what actually breaks, what is hard to reverse, and what most documentation and guidance doesn’t cover. We’ll walk through the critical design choices around identity coexistence, domain migrations, mail flow, and security, and show how those decisions impact both users and operations during and after the migration.

You’ll see what really gets migrated, what doesn’t, and where organizations often underestimate complexity. We’ll also cover common failure scenarios and how to avoid them, including issues with authentication, mail routing, and Defender visibility during transition phases.

The session includes practical examples and demos of migration workflows, showing how to maintain control, minimize downtime, and avoid introducing security gaps while moving between tenants.

If you’ve ever been part of a migration that didn’t go as planned or want to avoid being in one, this session is for you.