When you need to change your email service from Zimbra to Microsoft 365 just use a professional tool and follow these steps
Step 1. Open Tool and select scenario (IMAP to Office)
Step 2. Define Workload and add a Date filter
Step 3. Validate Admin Credentials
Step 4. Attach Users
Step 5. View, validate, and Start migration

Find more information at: https://www.office365tips.org/zimbra-to-microsoft-365-migration/