Moving 70 Mailboxes from Google Workspace to Exchange Online Without Losing a Message

Overview Email is the one system nobody notices until it stops working. When we moved a 70-person company from Google Workspace to Exchange Online, the goal wasn’t just “move the mail.” It was to move the mail without anyone missing a message, a calendar invite, or an automated workflow that quietly depended on a Gmail inbox. This post is the checklist I wish I’d had at the start. It’s written for small IT teams (often a team of one) doing a cutover without a migration partner.