We just finished migrating 120+ email accounts from Microsoft Exchange to Google Workspace. Zero downtime. Zero data loss. Zero complaints (well, almost zero - there's always someone).
Here's what we learned, what worked, what didn't, and what almost went wrong.
Why Migrate? The Business Case
This client had been on Exchange for years. It worked, but it was expensive. Really expensive. And managing it was becoming a nightmare.
Google Workspace offered:
- Better collaboration tools (Google Docs, Sheets, Drive)
- Lower costs (about 40% less than Exchange)
- Easier management (web-based, no servers to maintain)
- Better mobile experience
- More storage per user
But migration is risky. People rely on email. Lose their email, and you've got a real problem on your hands.
The Planning Phase (This is Where We Almost Screwed Up)
We started by auditing everything. And I mean everything:
- Total number of mailboxes (120+)
- Total amount of data (500+ GB)
- Shared mailboxes and distribution lists
- Email forwarding rules
- Calendars and contacts
- Archived emails
- Integration with other systems (Active Directory, SSO, etc.)
This took longer than expected. But it saved us later. We found mailboxes that hadn't been used in years, distribution lists that nobody knew existed, and email rules that were doing weird things.
Lesson learned: The planning phase is boring, but don't skip it. A thorough audit prevents problems during migration.
The Migration Strategy
We used a phased approach:
- Pilot migration (10 users): Test everything with a small group first
- Department-by-department: Migrate one department at a time
- Big-bang for shared resources: Migrate all shared mailboxes and calendars at once
- Cutover weekend: Final migration of remaining users
This approach let us:
- Fix issues before they affected everyone
- Learn from each phase
- Minimize disruption
- Have rollback plans for each phase
The Tools We Used
We tested several migration tools and settled on Google's Data Migration Service (DMS) plus GAM (Google Apps Manager) for automation:
- Google DMS: Handles the actual email migration
- GAM: Automated user creation, group management, and configuration
- PowerShell scripts: Extracted data from Exchange
- Custom tools: Validated migration success
GAM was a game-changer. Without it, we would have spent days creating users manually. With it, we automated 80% of the user setup.
What Went Right
Most things, actually. The migration was smoother than expected because:
- We tested everything in a dev environment first
- We had clear communication with users (weekly updates, migration schedule, training)
- We created comprehensive documentation
- We had a dedicated support channel during migration
- We migrated during low-usage periods
What Almost Went Wrong (And How We Fixed It)
Issue 1: Calendar conflicts
During the pilot, we found that some calendars had conflicts. The issue? Some events were in different timezones, and the migration tool didn't handle it well. We fixed this by normalizing timezones before migration.
Issue 2: Large mailboxes
A few users had mailboxes over 50GB. Google Workspace has limits, and these mailboxes would have exceeded them. We archived old emails first, then migrated only recent emails.
Issue 3: Shared mailboxes
Exchange shared mailboxes don't map directly to Google Workspace. We had to convert them to Google Groups or create delegated accounts. This required manual work, but we planned for it.
The Results
After everything was done:
- 120+ mailboxes migrated successfully
- 500+ GB of data transferred
- Zero downtime (we did the migration during scheduled maintenance windows)
- Zero data loss (we verified everything)
- 40% cost reduction
- Better collaboration (users loved Google Docs and Sheets)
Lessons Learned
Here's what I'd do differently (or the same) next time:
- Start with the audit. Know exactly what you're migrating before you start.
- Test everything. Set up a test environment. Migrate test accounts. Break things and fix them.
- Communicate constantly. Users hate surprises. Keep them informed.
- Have rollback plans. For each phase, know how to undo it if something goes wrong.
- Automate what you can. Tools like GAM saved us hours of manual work.
- Plan for edge cases. Large mailboxes, shared resources, integrations - they all need special handling.
- Train users. Google Workspace is different from Outlook. Users need training.
Your Next Steps
Planning a Google Workspace migration? Here's where to start:
- Audit your current email infrastructure
- Calculate the total amount of data you need to migrate
- Test with a pilot group first
- Create a detailed migration plan with rollback steps
- Communicate with users early and often
- Train your support team on Google Workspace
- Set up a test environment and practice
Email migrations are risky, but they don't have to be painful. With proper planning and testing, you can migrate without major issues.
Have questions about migrating to Google Workspace? Drop us a line - we love helping teams make this transition smoothly.