Migrating Microsoft 365 to Google Workspace
Consolidating a split email and document environment onto Google Workspace, with a restructured document library and zero data loss — including past employee data.
# Illustrative image, not actual client site.
The Scope & Requirements
- Fragmented Environment: Email was hosted on Microsoft 365, while documents were split across both Google Drive and Microsoft 365 (OneDrive/SharePoint) — creating duplication and inconsistent access across the business.
- Cost & Efficiency Drivers: The client wanted to consolidate onto a single platform to reduce licensing costs and improve operational efficiency.
- Document Library Restructure: Rather than a straight lift-and-shift, the client wanted their document library reorganised as part of the move.
- Former Employee Data: Past employees' mailboxes and documents needed to be migrated and retained alongside current staff data.
- Business Continuity: The move needed to run in parallel, with both platforms kept in sync, so staff could keep working without disruption or missed email during the transition.
- Data Integrity: Email, contacts, calendars, and documents needed to migrate accurately across every account, with no data loss or duplication.
Bilby Fusion's Approach
- Led by Ron Le Mesurier: Managed the end-to-end migration project, working directly with the client's team throughout the transition.
- Environment Assessment: Reviewed the existing Microsoft 365 tenant, user accounts, and mailbox and document sizes to plan the migration approach.
- Document Audit: Audited the client's documents across both Google Drive and Microsoft 365 to identify duplication and inform the restructured library design.
- Tool Selection: Selected Google Workspace's native migration tooling, suited to the number of users and the complexity of the mailboxes and documents being moved.
- Temporary Admin Access: Created a temporary Microsoft 365 account with Global Admin privileges, used to connect Google's migration tooling to the source tenant.
- Former Employee Accounts: Identified past employee mailboxes and documents requiring migration and retention alongside active user data.
- Parallel Run Strategy: Ran the mailbox migration in three passes, keeping Microsoft 365 and Google Workspace synchronised throughout the transition period.
The Solution
- Account Provisioning: Created and configured all user accounts in Google Workspace ahead of migration.
- Mailbox Migration: Migrated email, contacts, and calendars from Microsoft 365 to Google Workspace using Google's native migration tooling, connected via a temporary Global Admin account on the source tenant.
- Document Consolidation: Brought documents previously scattered across Google Drive and Microsoft 365 into a single, restructured library in Google Drive.
- Doc Library Restructure: Redesigned the folder and Shared Drive structure during the migration, rather than moving the existing document mess as-is.
- Former Employee Migration: Migrated past employees' mailboxes and documents into Google Workspace for ongoing retention and access.
- Three-Pass Sync: Ran the migration three times to capture new mail arriving during the transition, keeping both mailboxes in sync for a genuine parallel run.
- Parallel Run: Kept Microsoft 365 live alongside Google Workspace during the transition, giving the business time to validate before cutover.
- Zero Data Loss Cutover: Validated mail, contacts, and calendar data across every account before decommissioning Microsoft 365.
Business Outcomes
- Seamless Transition: Users moved to Google Workspace without losing any historical email, contacts, or calendar data.
- Cost Reduction: Consolidating email and documents onto a single platform reduced licensing costs.
- Reduced Duplication: A restructured document library removed the duplication caused by files sitting in both Google Drive and Microsoft 365.
- Improved Efficiency: Staff now work from one consistent platform and folder structure instead of two disconnected systems.
- Retained Historical Data: Past employees' email and documents were preserved and remain accessible for the business.
- No Business Disruption: Staff continued working throughout the migration, with no downtime or lost communications.
- Reduced Risk: The parallel run and repeated sync passes removed the risk of a single, high-stakes cutover.
Bilby Fusion's Value: Platform migrations are about more than moving data — they are about protecting business continuity while consolidating onto a platform that reduces cost and improves efficiency. By combining a document audit, a restructured library design, the right migration tooling, and a genuine parallel run, Bilby Fusion brought the client's fragmented email and document environment — including past employee data — together on Google Workspace with zero data loss and no disruption to the business.
Project Lifecycle
Discovery & Assessment
Review the Microsoft 365 tenant, user accounts, and mailbox and document sizes to plan the migration.
Document Audit & Design
Audit documents across Google Drive and Microsoft 365, and design the restructured library.
Temp Admin & Provisioning
Create a temporary Global Admin account on the source tenant, and provision all user accounts in Google Workspace.
Mailbox & Document Migration – Pass 1
Migrate email, contacts, calendars, and documents into the restructured library.
Sync – Pass 2 & 3
Re-run the migration to capture new mail and keep both platforms in sync.
Former Employee Migration
Migrate past employees' mailboxes and documents for ongoing retention.
Cutover & Decommission
Switch users fully to Google Workspace and decommission Microsoft 365.
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