Google Workspace to Exchange Online Migration

Problem

The client required migration from Google Workspace to Microsoft 365 to standardize collaboration, identity, and messaging services within the Microsoft ecosystem. The migration needed to preserve mailbox data, calendars, and contacts while minimizing disruption to end users and avoiding insecure manual export/import methods.

Solution

Designed and implemented a staged Google Workspace to Exchange Online migration using the built-in Google Workspace migration functionality in the Exchange Admin Center. The implementation included:

• Google Cloud service account configuration
• Domain-wide delegation setup
• Secure API authorization
• Exchange Online migration endpoint configuration
• Pilot mailbox validation
• Controlled migration batch execution

The migration approach prioritized secure delegated access, phased rollout, and validation before mail flow cutover.

Architecture

Google Workspace mailboxes were accessed through a dedicated Google Cloud service account configured with domain-wide delegation and OAuth scopes for Gmail, Calendar, Contacts, and People APIs.

Exchange Online connected to Google Workspace using the service account JSON key through the Exchange Admin Center migration endpoint. Mailbox data was synchronized into Microsoft 365 mailboxes before final DNS and MX record cutover.

Tech Stack

Microsoft 365 • Exchange Online • Google Workspace • Google Cloud Platform • Exchange Admin Center • Gmail API • OAuth 2.0 • Microsoft Entra ID

Outcome

• Successfully established secure delegated migration connectivity between Google Workspace and Microsoft 365
• Reduced migration complexity by leveraging Microsoft native migration tooling
• Enabled staged mailbox migration with pilot validation before production cutover
• Improved operational consistency by consolidating email services into Exchange Online

Key Takeaways

• Domain-wide delegation and OAuth scope configuration are critical for successful Google Workspace migration.
• Service account JSON keys should be handled as privileged credentials and securely managed.
• Pilot mailbox migrations significantly reduce production migration risk.
• Google API propagation delays can affect migration endpoint validation and should be accounted for during planning.

Reflection

Future improvements would include automating migration batch creation through PowerShell and integrating migration reporting dashboards for improved operational visibility during large-scale mailbox migrations.