Google Workspace to Microsoft 365 Migration Checklist

Moving from Google Workspace to Microsoft 365 looks like an email move. It's really a move of everything people use every day: mail, calendars, contacts, files, sign-ins and a lot of small habits. Most migration headaches come from something that wasn't on the list. This checklist is the list.

Before you start: decide why you're moving

Write down the reasons in a sentence or two: desktop Office apps, security and compliance features, one platform for a growing team, a client requirement. They'll guide every "do we bother moving this?" decision later.

Phase 1: Inventory

• Users. Every active account, plus former employees whose mailboxes you need to keep.
• Aliases and groups. Email aliases on each user, Google Groups used as distribution lists, and shared inboxes. Each needs a home in Microsoft 365 (an alias, a distribution list, a Microsoft 365 group or a shared mailbox).
• Shared drives and My Drive. How much data, who owns it, and how it's shared, especially files shared outside the company.
• Calendars. Shared calendars and room or equipment resources.
• Things that don't move cleanly. Google Forms, Google Sites and Apps Script automations have no automatic path into Microsoft 365. Each needs to be rebuilt (in Microsoft Forms, SharePoint or Power Automate) or retired.
• "Sign in with Google" apps. Any third-party service people log into with their Google account will need a new sign-in method.
• Devices. Phones and computers syncing Google mail, calendars or Drive.
• Retention and legal holds. Anything you're required to keep, and whether it's under a hold in Google today.

Phase 2: Plan

• Choose the Microsoft 365 licenses that match what people need. Don't buy the same plan for everyone by default.
• Map where every shared drive's files will land: OneDrive for personal files, SharePoint or Teams for shared ones.
• Decide the cutover window, usually an evening or weekend.
• Decide how long you'll keep the Google environment after cutover.
• Plan how you'll tell staff what's changing, when, and where to get help.

Phase 3: Prepare Microsoft 365

• Add and verify your domain in Microsoft 365, but don't change mail routing yet.
• Create users, shared mailboxes and groups.
• Turn on multi-factor authentication and sign-in protections before anyone starts using the new accounts.
• Set external sharing settings for SharePoint and OneDrive on purpose rather than accepting defaults.
• Configure email security and spam filtering.

Phase 4: DNS and email authentication

This is the part that breaks mail when it's rushed.

• A day or two ahead, lower the TTL on your MX records so the change takes effect quickly at cutover.
• Update SPF to include Microsoft 365, and remove Google once Google no longer sends mail for you.
• Set up DKIM signing in Microsoft 365. Google's DKIM key won't sign mail sent from Microsoft.
• Review your DMARC record and reports after cutover so legitimate mail isn't being rejected.
• Don't forget other services that send as your domain, such as your website forms, billing system or marketing platform.

Phase 5: Move the data

• Copy mail, calendars and contacts in stages before cutover, so the final sync is small.
• Be aware that Gmail labels become folders, and a message with several labels can end up in more than one folder.
• Copy files to their planned locations and check permissions on the other side.
• Spot-check a few users' mail, calendar and files before you call the copy done.

Phase 6: Cutover

• Switch MX records to Microsoft 365.
• Run a final sync for anything that arrived in Google after the main copy.
• Set up Outlook, Teams and OneDrive on computers, and reconnect phones.
• Remove old Google sync from devices, so people don't keep working in the wrong place.
• Have someone available as staff sign in on the first morning. Small problems fixed in minutes keep the whole move from feeling broken.

Phase 7: Clean up

• Rebuild or retire the forms, sites and automations you listed in phase 1.
• Switch "Sign in with Google" apps to new sign-in methods.
• Export anything you must retain from Google before you cancel it.
• Downgrade or cancel Google licenses only after everything is confirmed.
• Update your documentation: where each team's files live now, who administers what.

How long does it take?

It depends on the size of the organization: number of users, amount of mail and files, and how tangled the shared drives are. A realistic schedule comes out of the inventory, not before it.

Getting help

If you'd rather not run this yourself, our Google Workspace to Microsoft 365 migration project covers every phase above. After the move, our cloud services team handles Microsoft 365 day to day. Not sure whether to move at all? Schedule an IT assessment and we'll talk it through.