Case study · SMB / Professional Services · Chicago, USA
ITSECOPS consolidated a Chicago accounting firm from Google Workspace onto Microsoft 365 — zero hours of downtime, 100% of mail, calendar invites, contacts and files retained, and the new tenant hardened with MFA, DLP and Defender policies at no extra cost.
The client
A 60-person accounting firm in Chicago that had grown up on Google Workspace but whose clients, auditors and new hires all worked in Excel, Teams and the wider Microsoft ecosystem. Leadership wanted one platform — Microsoft 365 — without gambling a decade of client correspondence on the move.
The challenge
The switch was scheduled outside tax season, but even then the firm could not lose a day of email or a single client file. Retention rules for financial workpapers meant every message and attachment had to arrive intact and provable — and the new tenant had to be more secure than the old one, not less.
What we did
- Audited every mailbox, shared drive, group and calendar in Google Workspace and mapped each to its Microsoft 365 equivalent.
- Pre-migrated Gmail, Google Calendar, Contacts and Drive content to Exchange Online, Outlook and SharePoint/OneDrive while the firm kept working normally.
- Ran delta syncs until both platforms matched, then flipped MX records overnight — staff signed in to Outlook the next morning with their full history waiting.
- Reconciled per-mailbox and per-drive item counts to prove 100% retention — mail, calendar invites with attendees and recurrence, contacts and files.
- Hardened the new tenant as a complimentary add-on: MFA enforced through Conditional Access, DLP policies for client financial data, Microsoft Defender preset security policies, and SPF, DKIM and DMARC on the firm’s domain.
Results
- 0 hours of downtime — mail never stopped flowing and no working day was lost.
- 100% data retained — every mailbox, calendar invite, contact and file verified against source counts.
- A measurably stronger security posture on day one — MFA enforcement, DLP and Defender baselines included free with the migration.
FAQ
Does a Google Workspace to Microsoft 365 migration interrupt email?
No. All history is copied ahead of time and the MX cutover happens after a final delta sync, so mail keeps flowing throughout. In this project downtime was zero hours.
Do Google Drive permissions carry over to SharePoint?
Sharing is translated to Microsoft 365 permissions rather than copied blindly — owners, editors and viewers are mapped, and anything ambiguous is flagged for review instead of silently opened up.
What does the security hardening include?
For migrations we include MFA enforcement, baseline DLP policies, Defender preset security policies and email authentication (SPF, DKIM, DMARC) as standard — the new tenant goes live secure, not default.