Workstream 01
Inventory the behaviours that matter
Before choosing a tool, record every user’s primary mailbox, aliases, forwarding and delegation; then add shared calendars, meeting rooms and groups. Ask staff which workflows would make their day stop if they disappeared. This produces a much better scope than an employee count alone.
Also list non-human senders: the website contact form, accounting software, a CRM, printers and any application that sends from the company domain. These may not use a visible staff mailbox, but DNS or authentication changes can interrupt them.
What to capture before the decision
- Primary and shared mailboxes, aliases, forwarding and send-as permissions
- Personal and shared calendars, resources and recurring appointments
- Google My Drive versus team-owned Shared Drives
- Domain registrar, DNS control, SPF/DKIM/DMARC and third-party senders
- Device inventory: Windows, Mac and phones that need Outlook setup
Workstream 02
Decide where files should live
OneDrive is typically the natural destination for personal working files. SharePoint is often more suitable for team-owned repositories. Replicating an entire Shared Drive inside one employee’s OneDrive creates a new ownership risk, especially when that employee leaves.
Map one representative department’s permissions and Google-native files before running a broad transfer. Have the department owner open files, inspect conversion fidelity, and check both a normal colleague and an external guest account.
| Source item | Likely destination | Acceptance question |
|---|---|---|
| My Drive working documents | OneDrive | Can the owner open, edit and re-share the files? |
| Team-owned Shared Drive | SharePoint site/library | Are the correct business owners and groups in place? |
| Google Docs/Sheets/Slides | Converted Microsoft formats where appropriate | Do critical formulas, comments and links remain usable? |
| Shared calendar / room | Separately planned Exchange/Outlook setup | Can users find bookings and permissions after cutover? |
Workstream 03
Use a pilot that can fail usefully
A pilot made of the smallest, least complicated mailboxes proves little. Pick a normal employee, a large mailbox, someone with delegation and a team using shared files. Record expected results before testing, then compare the actual Outlook, SharePoint and calendar experience.
Keep both environments available through the agreed coexistence period where the migration method permits it. After final sync, validate inward and outward mail, aliases, mobile sign-in, recurring calendars, document access and the specific business workflows chosen in discovery.
Workstream 04
What should a quote separate?
Ask for distinct lines for mail/calendar/contact migration, Drive or Shared Drive work, identity and licence preparation, DNS cutover, Outlook/device setup, user training and aftercare. The quote should identify included data limits, the assumed number of devices, weekend charges and what the migration tool does not transfer.
A credible supplier should say which information is still unknown. If there is no plan for permission mapping, acceptance testing or residual Google Vault data, the scope is not yet complete.
What to capture before the decision
- Included mailboxes and maximum source data assumptions
- File-store destination map and conversion exceptions
- Cutover window, owner, test cases and rollback constraints
- What staff will see change on desktop/mobile
- Aftercare hours and separately chargeable tasks
Workstream 05
The exception log a migration team should actually maintain
Treat migration exceptions as decisions rather than a forgotten export of warnings. For each source object record the owner, destination, tool result, impact on the user, the remediation option and the person who has authority to accept the gap. A Google Forms workflow embedded in a department process is not made operational merely because its linked spreadsheet was copied. The same is true for Drive shortcuts, third-party add-ons, retained Gmail labels and meeting-room permissions. Identify these before the final sync rather than making the first Monday morning the discovery exercise.
Give the business a readable exception register with statuses such as resolved, workaround accepted, deferred with owner, and prevents cutover. A file that did not migrate is not automatically a failed project if it has a documented alternative; an undocumented critical file is. Record the evidence used to close each item, not just a green tick from the transfer tool.
| Evidence item | Example failure | Practical decision |
|---|---|---|
| Shared Drive ownership | Files copied to a departing employee's OneDrive | Move to a governed SharePoint location with named owners |
| Calendar delegation | Executive assistant cannot change meetings | Rebuild and test Outlook permissions with both users |
| Application mail | CRM invoices fail SPF or SMTP authentication | Inventory sender, then validate authorised sending after DNS change |
| Google-native file | Business-critical formula changes on conversion | Test conversion against a signed sample or retain a controlled original |
Workstream 06
Cutover-day rehearsal: prove the business journey
Agree a representative user journey: receive an external message, reply as a delegated identity, open an agreed team file, book a resource, sign in on a phone and complete a workflow that depends on a business application. Run it before migration and again at pilot sign-off. A user who can log into Outlook but cannot reach shared finance data has not passed acceptance.
Define a change freeze, service-desk contact, support window, accountable go/no-go owner and a safe recovery decision. DNS TTL changes, sync intervals, client-cache behaviour and external dependencies make recovery scenario-specific; do not promise that every completed migration can be instantly reversed.
What to capture before the decision
- Pilot covers high-risk users, not just the smallest accounts
- Each acceptance case has an expected result and named tester
- Exception register lists severity, workaround and owner
- Cutover communications cover affected devices and applications
- Residual source access and retention obligations are agreed
A useful next step is a source-and-target inventory, not a promise of instant zero-downtime migration.
Source documents and limitations
These references establish current vendor behaviour; they do not verify an individual customer's configuration or imply Microsoft affiliation. Technical claims should be rechecked before execution.