Move from Google Workspace to Microsoft 365 without losing a day of email

The short answer

To migrate Google Workspace to Microsoft 365, you set up Microsoft 365 alongside Google, copy data across while everyone keeps working in Gmail, then switch email delivery over in one planned cutover. Microsoft provides two free tools for this: the Google Workspace migration in the Exchange admin center for mail, calendars and contacts, and Migration Manager for Google Drive files.

Done in that order, staff lose little or no email time. Most of the work is in preparation: inventory, user setup, testing a pilot group, and a short list of things that do not migrate on their own. The steps below are the order we recommend for a 25 to 100 person business.

Before you start: decide what is moving

Write down everything your business uses in Google, not just Gmail. Typical items:

• User mailboxes, plus shared inboxes and email aliases such as info@ or billing@
• Google Groups used as distribution lists
• Calendars, including shared and resource calendars for rooms and equipment
• Contacts, both personal and shared
• My Drive files and shared drives
• Google Forms, Sites, Apps Script and third-party apps that sign in with Google
• Devices and printers that send email through Google, such as scanners

Microsoft’s tools cover mail, calendars, contacts and Drive files. Forms, Sites, scripts and app sign-ins need a separate plan, so list who owns each one.

Step 1: set up Microsoft 365

1. Buy licenses. Most businesses moving from Google Workspace Business Standard land on Microsoft 365 Business Standard or Business Premium.
2. Add and verify your domain in Microsoft 365 with the TXT record it gives you. Do not change MX records yet.
3. Create every user, shared mailbox and distribution group in Microsoft 365 with the same email addresses they have in Google. Microsoft’s migration guide requires users to be provisioned before migration starts.
4. Turn on multi-factor authentication for the new accounts before anyone signs in.
5. Make sure each user’s OneDrive exists. Microsoft’s Migration Manager guidance says standard projects need OneDrive provisioned before destinations are assigned; the Lite version can provision it automatically for eligible projects, and having each user sign in once also creates it.

Step 2: migrate email, calendars and contacts

Microsoft’s Exchange admin center offers an automated Google Workspace migration that moves mail and rules, calendars and contacts in batches. The prerequisites in Microsoft’s documentation include a Google Cloud project and service account with the right permissions, plus two routing subdomains so mail can flow between the two systems during the move.

Run a pilot batch of three to five people first, ideally one from each department. Check their mail, folders, calendar and contacts in Outlook, then migrate the rest in batches by team. The tool copies history while people keep working in Gmail, then keeps syncing new mail until you complete the batch.

What Microsoft says will not migrate

• Vacation and automatic reply settings
• Room bookings, shared calendars and event colors
• Contacts beyond three email addresses each, plus Gmail tags and custom contact fields
• Messages larger than your transport limit, which Microsoft says defaults to 35 MB

Mail rules do migrate but arrive turned off, so users need to review and enable them. Microsoft also recommends disabling any retention or archiving policies on the new mailboxes during the move, because they can make migrated items look missing.

Step 3: migrate Google Drive files

Migration Manager, found in the Microsoft 365 admin center under migration tools, copies files from My Drive and shared drives into OneDrive and SharePoint. Microsoft notes it makes copies, so the originals stay in Google until you delete them. For tenants with fewer than 300 licenses, a simplified version called Migration Manager Lite is turned on by default.

• Map each user’s My Drive to their OneDrive.
• Map each shared drive to a SharePoint site or Team. This is a good moment to tidy up, since shared drives often outgrow their original purpose.
• Check the permission settings. Microsoft says file-level permissions and older file versions need explicit settings to migrate.
• Download the scan and migration reports and review files that failed or are unsupported.

Plan Drive migration a few days before email cutover so the bulk copy is finished, then run a final incremental pass.

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Step 4: cut over with minimal downtime

1. One week before: lower the TTL on your MX record so the change spreads quickly. Tell staff the date and what will change.
2. Friday afternoon: run final syncs for mail and files. Freeze changes to shared drives.
3. Friday evening: change MX, SPF and autodiscover records to the Microsoft 365 values. Mail starts arriving in Microsoft 365 within minutes to hours.
4. Saturday: complete the migration batches so any mail that landed in Gmail during the switch is copied over. Set up DKIM for Microsoft 365 and update your DMARC record.
5. Monday morning: have someone available to set up Outlook on computers and phones, reconnect scanners and answer questions.

Common problems and how to avoid them

• Huge mailboxes slow everything down. Check mailbox sizes early and start the largest ones first, or agree to move only recent years and archive the rest.
• Shared inboxes get forgotten. A Google group used as a team inbox needs to become a shared mailbox in Microsoft 365, not a distribution list, or replies will come from the wrong address.
• Phones keep syncing Gmail. Remove the old Google account from phones on cutover day so people do not reply from the wrong system.
• Scanners and website forms stop sending. Anything that relays mail through Google needs new SMTP settings. Test each one before Monday.
• Nobody owns the timeline. Name one person who decides the cutover date and signs off each batch.

After the move

• Keep Google Workspace active for at least 30 days, with users blocked from sending, in case something was missed.
• Re-create vacation replies, room calendars and any shared calendars by hand.
• Update apps that used Sign in with Google to use Microsoft sign-in instead.
• Set up backups for Microsoft 365. The platform includes recycle bins and version history, but those are not a substitute for a separate backup with tested restores.
• Cancel Google licenses only after you confirm nothing else depends on them.

If you are still deciding between the two platforms, our comparison of Microsoft 365 vs Google Workspace covers cost and fit. JLB USA plans and runs these moves as part of managed IT for businesses with roughly 25 to 100 employees, with replies within 5 minutes by email or phone and on-site help in Atlanta, Birmingham and Chattanooga.

Keep reading

• Microsoft Teams Phone for small business: can it replace your phone system?
• Mobile device management for small business: what it does and how to roll it out
• Microsoft 365 Business Standard vs Premium: which plan should you buy?
• Chattanooga IT support: a buyer's guide for growing businesses

Related services

• Managed IT services
• Microsoft 365 vs Google Workspace
• Microsoft 365 security settings
• Free Technology Health Assessment