The decision, and why it splits into three projects
Organizations that ask whether to leave Google Workspace usually have the business reason already: a parent company or acquirer on Microsoft 365, a line-of-business application built for Outlook and Excel, a compliance program designed around Microsoft Purview, or a workforce that already lives in Teams. The harder question is what the move involves, and EPC Group answers it by splitting the estate into workloads. Microsoft documents that mail and rules, calendar and contacts can be migrated from Google Workspace, in batches of users, so that the project runs in stages (Microsoft Learn, Perform a Google Workspace (formerly G Suite) migration to Microsoft 365 or Office 365, accessed 2026-10-20). Files in personal and shared drives move through Migration Manager, which copies Google Workspace files, metadata and permissions to OneDrive and SharePoint (Microsoft Learn, Migrate Google Workspace to Microsoft 365 with Migration Manager, accessed 2026-10-20). Everything else, including Google Sites, Apps Script and third-party apps that sign users in with Google, is a rebuild decision rather than a copy job. EPC Group's Microsoft 365 consulting practice runs the decision and the plan as one engagement, because the honest answer to "should we move" depends on how long that rebuild list is.
What migrates from Google Workspace, and what does not
For mail, Microsoft lists filtering options for Mail, Calendar, Contacts and Rules in the automated migration, and it is equally specific about the gaps. Vacation and automatic reply settings, room bookings, shared calendars, event colors, Gmail tags, contact URLs and custom tags are not migrated; contacts carry a maximum of three email addresses each; and the default single-message limit is 35 MB, configurable up to 150 MB (Microsoft Learn, Google Workspace automated batch mail migration overview, accessed 2026-10-20). Microsoft also strongly recommends disabling messaging records management tools and archival policies before any data migration, because they cause perceived data loss during verification checks (same source).
For files, the Google Export API converts Google Docs to .docx, Sheets to .xlsx and Slides to .pptx, Google Drawings arrive as PNG files, and Google Forms migrate when a Forms destination is designated. Google Sites and Google Maps are not migrated, and unorganized or orphaned files are not scanned, migrated or shown in any report (Microsoft Learn, Unsupported files in Migration Manager, accessed 2026-10-20). Conversion is a format change, not a fidelity guarantee. EPC Group samples converted files that carry heavy formulas, Apps Script bindings or embedded charts, and gives each problem file an owner before cutover. Google Sites become SharePoint sites built by hand, which is usually the right moment to redesign the intranet instead of reproducing it. Shared drives map to SharePoint or Teams sites, with identity mapping deciding who keeps access.
Identities, licenses and mail routing come first
The Exchange migration expects identities to exist before any mail moves. Microsoft requires every migrated user to be provisioned as a mail-enabled user outside the migration process and assumes the Microsoft 365 domain is verified (Microsoft Learn, Perform a Google Workspace (formerly G Suite) migration to Microsoft 365 or Office 365, accessed 2026-10-20). The automated method has four prerequisites: a subdomain in Google Workspace that routes mail to Microsoft 365, a subdomain that routes mail back to Google Workspace, provisioning the mail users, and verifying Google migration administrator role assignments (Microsoft Learn, Google Workspace automated batch mail migration overview, accessed 2026-10-20). The business guide adds that DNS changes can take up to 72 hours to be recognized, that forwarding must be allowed in both Google Workspace and Exchange Online, where outbound spam policies, Remote Domain settings and mail flow rules can each block it, and that Exchange licenses are assigned after the batch completes (Microsoft Learn, Migrate business email and calendar from Google Workspace, accessed 2026-10-20).
The file side has its own access model. Migration Manager needs a OneDrive or SharePoint admin, a user with the Microsoft 365 Migration Administrator role, or a Global admin in the destination tenant, plus a Google Workspace administrator who can install and authorize the Microsoft 365 Migration app (Microsoft Learn, Migrate Google Workspace to Microsoft 365 with Migration Manager, accessed 2026-10-20). EPC Group creates accounts from the HR system rather than from the Google directory, maps every Google group to a Microsoft 365 group before the first scan, enforces multifactor authentication before the pilot, and gives migration operators the Microsoft 365 Migration Administrator role instead of Global admin.
Coexistence while batches run
Coexistence is mostly a mail-routing problem. The routing subdomains let mail for a migrated user land in Microsoft 365 while unmigrated colleagues stay on Gmail. Each batch performs an initial copy and incremental syncs, shows Syncing and then Synced, and is completed by the administrator when the team is ready (Microsoft Learn, Perform an automated Google Workspace migration to Microsoft 365 or Office 365 in EAC in Exchange Online, accessed 2026-10-20). On the file side, selecting Migrate again on a completed task starts a delta sync that, by default, transfers only new or modified files, and a destination file with a newer modification time is not overwritten (Microsoft Learn, Frequently Asked Questions: Migration Manager Google, accessed 2026-10-20). Microsoft's consolidated guidance sends tenants with more than 1,000 source users to a large tenant migration experience built to keep both Google Workspace mail and Exchange Online usable for the duration, and smaller tenants to the simplified Gmail migration (Microsoft Learn, Consolidated migration of data from Google Workspace to Microsoft 365 Exchange, accessed 2026-10-20).
EPC Group's coexistence rules are short. Migrate by team, not alphabetically, so that calendars and shared drives move with the people who use them. Freeze renames and moves on source folders, because Microsoft warns that changed paths can cause content to be copied again and create duplicates (Microsoft Learn, Step 6: Migrate and monitor your Google migration, accessed 2026-10-20). Keep Google accounts available read-only for a defined window after cutover. And switch the MX record only when the last batch shows Synced.
Sizing the plan: 15, 150 or 1,500 users, and nonprofits
Microsoft's own tooling changes with size. Migration Manager Lite, a guided wizard that folds task selection, destination assignment, identity mapping and settings into one flow, is enabled by default for tenants with fewer than 300 Microsoft 365 licenses (Microsoft Learn, Migrate Google Workspace to Microsoft 365 with Migration Manager, accessed 2026-10-20). In standard Migration Manager, a single Google Drive task should not exceed 100,000 items or 1 TB, and larger drives are split into tasks by root folder with a CSV upload (Microsoft Learn, Step 2: Scan and assess Google Drives, accessed 2026-10-20). EPC Group plans a 15-user organization as a short project with one mail batch, Migration Manager Lite and a weekend cutover. A 150-user organization runs a pilot group, then department batches, with device and identity work alongside. At 1,500 users the plan becomes a program with discovery, the large tenant mail experience, split drive tasks, a champions network and several cutover waves.
Nonprofits have an extra licensing step. Microsoft for Nonprofits makes Microsoft 365 grants available to registered nonprofits through the Nonprofit Hub, where an approved organization activates the offer and then assigns licenses (Microsoft Learn, Accessing M365 Grants, accessed 2026-10-20). Microsoft allows one validated grant tenant per organization and treats failure to maintain at least 85% active usage of granted licenses as program abuse (Microsoft Learn, Eligibility guidelines, accessed 2026-10-20). EPC Group confirms eligibility and the grant tenant before anyone is provisioned, because migrating into the wrong tenant means doing the move twice. For the adoption side of any size, the adoption and change management practice runs training on Outlook, OneDrive and Teams before the first batch completes.
Documented work
ANON-CASES: EPC Group engagement data for Google Workspace to Microsoft 365 migration covers a mid-size education and training organization moving mail, calendars and shared drives to Exchange Online, OneDrive and SharePoint, with Google Sites rebuilt as SharePoint sites, delivered by the firm's Microsoft 365 consulting and cloud migration practices. Client names are not published here. Engagements are described by industry and organization size only, and no outcome figures are quoted that cannot be traced to a signed deliverable. EPC Group is a Microsoft Solutions Partner with all six Solutions Partner Designations as of October 2026.
Primary sources
- Perform a Google Workspace (formerly G Suite) migration to Microsoft 365 or Office 365 — Microsoft Learn, accessed 2026-10-20
- Google Workspace automated batch mail migration overview — Microsoft Learn, accessed 2026-10-20
- Perform an automated Google Workspace migration to Microsoft 365 or Office 365 in EAC in Exchange Online — Microsoft Learn, accessed 2026-10-20
- Consolidated migration of data from Google Workspace to Microsoft 365 Exchange — Microsoft Learn, accessed 2026-10-20
- Migrate business email and calendar from Google Workspace — Microsoft Learn, accessed 2026-10-20
- Migrate Google Workspace to Microsoft 365 with Migration Manager — Microsoft Learn, accessed 2026-10-20
- Unsupported files in Migration Manager — Microsoft Learn, accessed 2026-10-20
- Step 2: Scan and assess Google Drives — Microsoft Learn, accessed 2026-10-20
- Step 6: Migrate and monitor your Google migration — Microsoft Learn, accessed 2026-10-20
- Frequently Asked Questions: Migration Manager Google — Microsoft Learn, accessed 2026-10-20
- Accessing M365 Grants — Microsoft Learn, accessed 2026-10-20
- Eligibility guidelines — Microsoft Learn, accessed 2026-10-20
Frequently Asked Questions
What migrates cleanly and what needs rework (Docs formats, shared drives, Sites)?
Mail, calendar, contacts and Gmail rules migrate through the Exchange batch tooling, with gaps Microsoft lists: vacation and automatic reply settings, room bookings, shared calendars, event colors and Gmail tags stay behind (Microsoft Learn, Google Workspace automated batch mail migration overview, accessed 2026-10-20). Migration Manager converts Docs, Sheets and Slides to .docx, .xlsx and .pptx, migrates Drawings as PNG files and Forms to a designated Forms destination, and does not migrate Google Sites or Google Maps (Microsoft Learn, Unsupported files in Migration Manager, accessed 2026-10-20). Shared drives map to SharePoint or Teams sites. EPC Group treats Sites, Apps Script and complex spreadsheets as a rework list with named owners.
How are identities and licenses prepared?
Microsoft requires every user in a batch to be provisioned as a mail-enabled user outside the migration process, with the Microsoft 365 domain already verified (Microsoft Learn, Perform a Google Workspace (formerly G Suite) migration to Microsoft 365 or Office 365, accessed 2026-10-20). The business guide has admins create mail users whose external address is the Google routing address, add a Microsoft 365 routing alias to each one, and assign Exchange licenses after the batch completes (Microsoft Learn, Migrate business email and calendar from Google Workspace, accessed 2026-10-20). EPC Group builds the user list from the HR system, maps every Google group to a Microsoft 365 group, and enforces multifactor authentication before the pilot batch.
How is coexistence handled during the move?
Two routing subdomains, one pointing to Microsoft 365 and one back to Google Workspace, let mail reach migrated and unmigrated users while batches run (Microsoft Learn, Google Workspace automated batch mail migration overview, accessed 2026-10-20). A batch moves from Syncing to Synced and is then completed by the administrator (Microsoft Learn, Perform an automated Google Workspace migration to Microsoft 365 or Office 365 in EAC in Exchange Online, accessed 2026-10-20). For tenants above 1,000 source users, Microsoft directs admins to a large tenant experience designed to keep both mail systems usable during the migration (Microsoft Learn, Consolidated migration of data from Google Workspace to Microsoft 365 Exchange, accessed 2026-10-20). EPC Group migrates by team and switches the MX record last.
What does the nonprofit licensing path look like (Microsoft, attributed)?
Microsoft for Nonprofits makes Microsoft 365 grants available to registered nonprofits: an approved organization chooses the grant on the Nonprofit Hub, activates it in the admin portal and assigns licenses, or moves existing users onto the grant licenses (Microsoft Learn, Accessing M365 Grants, accessed 2026-10-20). Microsoft allows one validated grant tenant per organization, lists government bodies, schools and financial institutions among ineligible organizations, and expects at least 85% active usage of granted licenses (Microsoft Learn, Eligibility guidelines, accessed 2026-10-20). EPC Group confirms eligibility and the grant tenant before any user is provisioned, and reads the current offer list on the Nonprofit Hub at decision time.
How long does a 15-, 150- or 1,500-user migration take?
Microsoft sizes the tooling rather than the calendar. Migration Manager Lite is on by default for tenants with fewer than 300 licenses (Microsoft Learn, Migrate Google Workspace to Microsoft 365 with Migration Manager, accessed 2026-10-20), a drive task should stay under 100,000 items or 1 TB (Microsoft Learn, Step 2: Scan and assess Google Drives, accessed 2026-10-20), and DNS changes can take up to 72 hours to be recognized (Microsoft Learn, Migrate business email and calendar from Google Workspace, accessed 2026-10-20). In EPC Group planning, 15 users is a short project with one cutover, 150 users runs a pilot and department waves over several weeks, and 1,500 users is a multi-month program. Rebuild scope, not data volume, sets the pace.
Talk to a senior architect
If your organization is weighing a move off Google Workspace, a 30-minute discovery call with a senior EPC Group architect sorts the estate into what migrates, what converts and what must be rebuilt, and sets out the batch plan. See the Microsoft 365 consulting service hub for engagement structures.
Email contact@epcgroup.net or call 888-381-9725.
a Microsoft Gold Partner (2000 until Microsoft retired the program in 2022) — today holding all six Microsoft Solutions Partner Designations.
Documented engagements
Each record publishes a redacted primary-source document — a client purchase order, executed agreement or payment record — with a SHA-256 hash you can recompute, and states what the document does not establish.
- Prairie View A&M University — Contracted — public procurement record