Business Email Migration Checklist: Mailboxes, History and Cutover
Move the mailboxes and verify their history before closing the old email account. Changing MX records sends new incoming messages toward a destination; it does not transfer the messages already stored at the previous provider.
Define what must move
Inventory users, shared addresses, aliases, groups, forwarding rules and mailbox sizes. Include calendar and contact requirements as separate items. Ask the destination provider which data its chosen migration method supports and what it leaves behind.
Google’s IMAP migration guidance concerns importing email from an IMAP server into Workspace. That is a specific source, destination and method, not a promise that every mailbox setting or collaboration feature will transfer. Match the tool to your source system before booking a cutover.
Map addresses and permissions
Create a source-to-destination record for each mailbox. Confirm the people who need access, the administrator who approves the move and the ownership of shared addresses. Test destination sign-in before directing incoming mail there.
Do not collect passwords in a shared spreadsheet. Use the provider’s supported authorization process and a private method for any required credentials. Record authorization status and responsible owners in the plan; the plan itself should not become a secret store.
| Check | Evidence to record | Next decision |
|---|---|---|
| Address map | Source, destination and mailbox owner | Resolve missing or duplicate recipients |
| Data scope | Email, folders, dates and separately handled features | Confirm what the migration method supports |
| Pilot mailbox | Sample history and failed-item report | Adjust scope before moving everyone |
| Cutover | MX plan, service overlap and communication owner | Choose a supervised change window |
| Final reconciliation | Recent mail, aliases and user access | Approve retirement of the old service |
Pilot a representative mailbox
Choose an authorized test mailbox with older messages, nested folders, attachments and recent activity. Check that the destination contains usable examples rather than relying only on a progress percentage. Save the migration report and investigate skipped or failed items.
Message counts are useful, but differing folder models and duplicate handling can make totals hard to compare. Agree a reconciliation method with the mail administrator. Sample several dates and important folders, and verify that attachments can be opened in the destination.
Cut over new delivery carefully
Prepare the destination recipients and follow the receiving provider’s current DNS instructions. Record the old routing, new routing, change time and escalation contact. Verify public MX values and send external test messages to critical addresses.
Keep the source accessible during the agreed overlap. Check whether the migration tool supports a final pass for mail arriving after the first import. Define how you will catch late arrivals at the old service rather than assuming that all senders see the new records immediately.
Retire the old service after sign-off
Test sending, receiving, aliases, shared mailbox access and supported mail clients. Check authentication for the new sender through SPF and DKIM. Website notifications may use a separate delivery service and need their own tests.
Document who approved data reconciliation and when the old account may be cancelled. Retain exports or other agreed recovery material under the business’s access and retention rules. Confirm which domain or website services are bundled with the old subscription before terminating it.
A migration is complete when the expected data and working mail workflows have been accepted by the owners. A successful DNS lookup or a finished import screen alone is not that acceptance.
Separate historical completeness from new delivery
A hypothetical mailbox receives new messages after cutover, but an older folder is absent. Keep current routing and historical transfer as separate acceptance items. Compare the agreed folder and date scope against the migration result, then investigate omissions with the transfer owner. Do not retire the old service merely because today’s mail arrives; retain access until the agreed history and permissions have been checked.
Sources and scope
Official documentation checked October 6, 2026: Google Workspace: IMAP migration; Google Workspace: MX setup. This is HRL’s general operating checklist, not a test of your domain or a guarantee of delivery, recovery or search visibility.
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