Moving From Google Workspace to Microsoft 365: What to Plan For
Microsoft's migration tools will copy your email and files. They won't tell you which apps still sign in with Google, which shared drives lose their members, or what to lock down before the first phishing email arrives.
July 2026
Google Workspace is a good platform, and we support businesses that run on it. But we hear the same reasons again and again from companies that decide to move: their clients and partners live in Microsoft Teams, their finance team needs desktop Excel, or they want the security and device management that come with Microsoft 365 Business Premium.
The good news is that Microsoft has built tools for both halves of the move. The Exchange admin center can migrate Gmail mailboxes, calendars and contacts, and Migration Manager copies Google Drive into OneDrive and SharePoint. For organizations with fewer than 300 licenses, Microsoft turns on a simplified version called Migration Manager Lite by default.
The bad news is that copying data is the easy part. The problems that cause downtime come from the things the tools don't move, and from the systems nobody remembered were connected to Google.
What moves, and how
Email, calendars and contacts
The Exchange admin center has a built-in Google Workspace migration type. It connects to Gmail through a Google service account and copies mail, calendar, contacts and rules into Exchange Online. Temporary routing subdomains keep mail flowing to both systems while batches run.
Google Drive and shared drives
Migration Manager copies personal drives into OneDrive and shared drives into SharePoint or Teams. Google Docs, Sheets and Slides are converted to Word, Excel and PowerPoint, and file versions and Google Forms can come across too. The originals stay untouched in Google Drive.
Changes made during the project
Running a Migration Manager task again performs a delta sync that picks up new and changed files. That lets us copy the bulk of the data weeks early and run a short final pass at cutover.
What doesn't come across
Microsoft publishes a list of what Migration Manager skips. These are the items that matter most for a typical business, and each one needs a plan before cutover, not after.
Comments and ownership history on Google Docs.
Apps Script and macros. Microsoft also says Sheets formulas don't migrate, so test the spreadsheets you rely on.
Google Sites. Google Drawings come across as PNG images.
Links inside documents still point at Google Drive.
Shared drive membership and anything shared with outside guests. These have to be re-shared.
"Orphaned" files with no folder location. They aren't scanned, migrated or reported.
File-level permissions, unless you enable them. By default, files inherit the permissions of the destination folder.
Trashed items and files marked restricted or not copyable.
The gotchas that actually cause downtime
Apps that sign in with Google
CRMs, accounting tools, scheduling apps and project tools where staff click "Sign in with Google" will break the day those Google accounts go away. The Google admin console can list the third-party apps connected to your users. Inventory them first and switch each one to a Microsoft sign-in or a local account before cutover.
DNS and mail cutover
Moving your MX records is the moment email starts arriving in Microsoft 365. Lower DNS time-to-live values days in advance, cut over outside business hours, and update SPF, DKIM and DMARC for Microsoft so your outbound mail doesn't land in spam.
Retention and archiving policies
Microsoft strongly recommends disabling retention and archival policies before migrating mailboxes. Otherwise items those policies move or delete get flagged as "missing," and real data loss becomes much harder to spot during verification.
Groups, shared inboxes and conference rooms
Google Groups, shared mailboxes and room calendars need to exist in Microsoft 365 before cutover, as Microsoft 365 Groups, distribution lists, shared mailboxes and room mailboxes. If they don't, mail to sales@ or bookings for the conference room fails quietly.
Phones and the first Monday morning
Every phone needs Outlook, Teams and OneDrive set up, and every user needs to know where their files went. A short how-to sheet and someone on call on day one prevent most of the help desk tickets.
How we run a migration
The goal is that your team finishes work in Google on a Friday and starts in Microsoft 365 on Monday with their email, files and calendar already waiting. That only happens when most of the work is done before anyone notices.
Discovery
Users, mailbox and Drive sizes, shared drives, groups, third-party apps signing in with Google, DNS records, and any retention or legal-hold requirements.
Build and secure the tenant first
Accounts, licensing, MFA, Conditional Access, device management and email protection are in place before any data lands.
Pilot
A small group moves first so we can validate mail, calendars, file permissions and app sign-ins with real users.
Pre-stage the data
Bulk email and file copies run in the background while everyone keeps working in Google.
Cutover
MX and DNS changes happen after hours, followed by a final delta sync of mail and files.
Day-one support
Phone setup, quick training and someone on call while your team settles in.
Decommission Google
After a holding period, we confirm nothing is still pointing at Google and export anything you must retain. Only then do you cancel the Google subscription.
Secure the new tenant before the data lands
A new Microsoft 365 tenant is at its most exposed in the weeks around a migration. Users are expecting unfamiliar sign-in prompts and "your account has moved" emails, which is exactly what a phisher would send them.
That risk is not theoretical. In May 2026 the FBI warned about Kali365, a phishing kit sold on Telegram that tricks users into typing a code into Microsoft's real sign-in page. The attacker walks away with tokens that open Outlook, Teams and OneDrive without a password and without another MFA prompt. The FBI's first recommendation was a Conditional Access policy that blocks the "device code" sign-in flow for everyone who doesn't need it.
That is why we configure security first, then move data. On every migration we set up:
MFA for every account, with phishing-resistant methods for admins.
Conditional Access that blocks legacy authentication and the device code flow.
Device management with Intune so company data stays on managed laptops and phones.
Defender for Office 365 protection against phishing links and malicious attachments.
Separate admin accounts so a compromised user can't change tenant settings.
Alerting on risky sign-ins, new inbox forwarding rules and unusual app consents.
Frequently asked questions
Will we lose email during a Google Workspace to Microsoft 365 migration?
Not if it is planned properly. Mail keeps flowing to Google until the MX cutover, and the migration copies existing mail without removing it from Gmail. A final sync after cutover picks up anything that arrived in between.
Do Google Docs and Sheets convert to Word and Excel?
Yes. Migration Manager converts Docs to Word, Sheets to Excel and Slides to PowerPoint. Apps Script and macros don't come across, and Microsoft says Sheets formulas aren't migrated either, so test the spreadsheets your team depends on before cutover.
How long does the migration take?
Most of the time goes into planning and pre-staging data while your team keeps working in Google. The cutover itself is scheduled outside business hours, so the part your team experiences is short.
Which Microsoft 365 plan should we choose?
For most small and mid-sized businesses, Microsoft 365 Business Premium. It includes Conditional Access, Intune device management and Defender protection, which are the controls you need to secure the new tenant. Business plans are capped at 300 users.
Can we do the migration ourselves?
Microsoft's tools make a do-it-yourself migration possible for a small, simple environment. Most of the risk sits in the details: apps that sign in with Google, DNS timing, permissions and security configuration. Those are what an experienced partner gets right the first time.
Planning a move to Microsoft 365?
We plan the cutover, move the data, secure the new tenant and stay on call for your team's first week, so the switch is a weekend, not a crisis.
Related Services & Resources
Victor Peralta
Co-Founder & CEO
Vigil Cyber provides 24/7 managed security operations for small and mid-sized businesses across the Southeast. Our team combines rigorous operational discipline with enterprise security expertise.
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