After a merger, two Microsoft 365 tenants had to become one. I planned and led the consolidation across identity, mail, and Teams.
Context
Following a merger, the organization ran two Microsoft 365 tenants with overlapping identities and duplicated collaboration estates.
Challenge
Two tenants meant duplicated identity, inconsistent governance, and a fractured experience that slowed the combined business.
Scope
- Plan tenant-to-tenant migration
- Consolidate identity and mail
- Migrate Teams and collaboration content
- Unify governance
Constraints
- Minimal disruption to a live, merged workforce
- Overlapping identities and naming
- Tight cutover windows
Approach
- 01Sequenced identity, mail, and collaboration migration to limit disruption
- 02Resolved identity and naming overlaps before cutover
- 03Migrated Teams and content with clear user communication
- 04Established one governance model for the consolidated tenant
Technologies
Microsoft 365Entra IDTeamsMigration Tooling
Microsoft 365
Entra IDOutcome
- A single, consistently governed tenant
- Duplicated identity and collaboration estates removed
- One coherent collaboration model for the merged business
Lessons
Tenant consolidation is a people project as much as a technical one. Communication and sequencing prevent most of the pain.
What made it complex
Merging live identity and collaboration estates without interrupting a workforce mid-integration.
Azure Landing Zones
Azure Policy
Microsoft Sentinel
Defender XDR
KQL
Conditional Access