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Consulting / Email migration

Google ↔ Microsoft 365.

Switch email, calendar, contacts, and shared file storage across the two big productivity suites — with zero lost messages, minimal disruption, and a documented cutover plan that explains every step.

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Why this matters

Email migration is one of those projects that looks simple from the outside and is full of sharp edges from the inside. Mailbox size limits, calendar invites that point at the old tenant, distribution lists that nobody owns, shared drives with byzantine permission trees, contacts that live in three places. A migration done badly costs you a quarter of staff productivity. A migration done well is invisible to end users — they sign into the new tenant Monday morning and everything is where it should be.

Two directions, same playbook

What we deliver, end to end.

Google Workspace → Microsoft 365

  • Full mailbox migration (mail, calendar, contacts) with attachment fidelity
  • Drive → OneDrive (personal) + SharePoint (shared) with permission mapping
  • Google Groups → Exchange distribution lists / Microsoft 365 groups
  • Shared drives → SharePoint sites with site-collection planning
  • Google Sites → SharePoint pages where applicable
  • Calendar resource migration (rooms, equipment) with booking continuity

Microsoft 365 → Google Workspace

  • Full mailbox migration (mail, calendar, contacts) with attachment fidelity
  • OneDrive / SharePoint → Drive with permission mapping
  • Distribution lists → Google Groups
  • Teams data → Chat / Spaces with channel mapping
  • SharePoint sites → Drive shared drives + Google Sites
  • Resource calendar migration with booking continuity

The shape of every engagement

Five phases, one clear runbook.

  1. 1

    Discovery

    Week 1

    Mailbox sizes, attachment counts, distribution lists, shared drives, custom integrations inventory. Output: a written migration plan with risks, sequence, and the cutover-window recommendation.

  2. 2

    Pre-cutover validation

    Week 1–2

    Sample mailbox migrations to validate fidelity, archive consolidation, attachment sanity-check, distribution-list owner outreach. Surface every issue before cutover-day.

  3. 3

    Coexistence period

    Week 2–4

    Mail forwarding + calendar free/busy sharing across both tenants so the transition does not have to be instant. Buys you time to fix the long tail of migration edge cases.

  4. 4

    Cutover

    One weekend

    MX record flip, final delta sync, sign-in updates, helpdesk readiness. Documented runbook + rollback plan that you keep regardless of outcome.

  5. 5

    Post-cutover safety net

    First 30 days

    Search-and-find access to the source tenant for 30 days, daily delta-sync of any straggling mail, decommission plan executed at end-of-window.

Education

What buyers should understand before signing.

"Migrate" is the last 20%

The actual mail-move is the easy part — modern tooling makes it largely mechanical. The 80% that determines success is everything around it: shared mailbox ownership, calendar delegations, send-as permissions, distribution list ownership, mail-flow rules, third-party integrations (e-sign, CRM, marketing, analytics) that authenticate against the old tenant. Pre-cutover discovery is where this work happens.

Why "coexistence period" matters

Cutover-day-as-instant-cutover is a trap. Coexistence — where both tenants can route mail to each other and read each other's free/busy — buys you a week or two of safety net while the long tail of edge cases gets fixed. Customers who skip coexistence almost always regret it by Tuesday morning of cutover week.

What the runbook contains

A real cutover runbook is timestamped, owner-tagged, dependency-mapped, and rollback-aware. Every step says: who does it, what time, what the success-check looks like, and what the rollback is if it fails. You keep the runbook regardless of whether you stay with us afterward — your team can replay or reverse it.

Sizing the project honestly

Tenants under 50 users and under 1 TB of mail are usually 2–3 weeks. 50–250 users with shared drives + custom integrations land at 4–6 weeks. Anything past 250 users or regulated-data sensitivity benefits from a Pro3 Master architecture review on top of the standard Pro2 lead.

Ready for a migration discovery conversation?

Tell us the source tenant, the destination tenant, the user count, and the rough timeline. We will come back with a written plan + quote within five business days.

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