GUIDE

Moving to Microsoft 365 or Google Workspace without downtime

Darshan Savkar (opens in new tab) · Published 17 October 2026 · Last reviewed 17 October 2026 · 3 min read

1. Take stock before you touch anything

• ☐List every mailbox, alias, shared mailbox, distribution list and forwarding rule. Shared and forgotten addresses are what usually breaks.
• ☐Note how much mail each person has and how far back it needs to go.
• ☐List what else lives in the old system: calendars, contacts, shared files, room bookings.
• ☐Find out who controls your domain’s DNS, and make sure you can log in. Without it, nothing else can happen.
• ☐List devices and apps that send email: scanners, websites, accounting software, alerts. They need new settings too.
• ☐Buy the licences you need on the new platform, on an account your company owns.

2. Prepare the new service

• ☐Verify your domain on the new platform. Both Microsoft 365 and Google Workspace do this with a DNS record.
• ☐Create the users, shared mailboxes and groups to match your list, with MFA turned on from the start.
• ☐A day or two before the switch, lower the TTL on your MX records (for example to 5 minutes), so the change takes effect quickly when you make it.
• ☐Tell staff the date, what will change on their phones and laptops, and who to contact.

3. Copy mail before the switch

Both platforms include migration tools for common sources, such as IMAP servers, Exchange and each other. See Microsoft: ways to migrate email to Microsoft 365 (opens in new tab) and Google Workspace: import email with the data import tool (opens in new tab). Copy older mail first, while everyone keeps working in the old system. That way the final copy after the switch is small and quick.

4. Switch over at a quiet time

• ☐Change the MX records to the new service, outside working hours or on a weekend.
• ☐Update SPF to authorise the new service, publish its DKIM key, and add a DMARC record. Start DMARC at p=none to watch the reports, then move to quarantine once legitimate mail passes.
• ☐Run the final copy so the last few days of mail arrive in the new mailboxes.
• ☐Reconnect phones, Outlook or Gmail, and the devices and apps that send email.
• ☐Send and receive test messages from outside the company, including to and from a Gmail and an Outlook.com address.

5. After the switch

• ☐Keep the old service running for a few weeks, so nothing in flight is lost and you can check for missed mail.
• ☐Raise the MX TTL again once everything is stable.
• ☐Check DMARC reports for any service still sending as your domain from the old setup.
• ☐Cancel the old service only after a final check, and keep an export if you need it for records.

Common mistakes

• Forgetting shared mailboxes, aliases or forwarding rules, so some addresses silently stop working.
• Not lowering the TTL first, so mail keeps arriving at the old service for hours or days.
• Leaving SPF pointing only at the old provider, so the new service’s mail lands in spam.
• Cancelling the old service on day one, before the final copy and checks.

Sources

• Microsoft: ways to migrate email to Microsoft 365 (opens in new tab)
• Google Workspace: import email with the data import tool (opens in new tab)

This guide is general information, not legal advice. Laws and standards change; check the primary sources linked below, and ask your lawyer how they apply to your business. See our editorial and claims policy for how we write and review guides. Found an error? Email hello@zaivit.com with the subject "Correction".