Business Email Migration Checklist

Keep source and destination roles explicit, then use an initial sync and final delta when the source supports reliable IMAP access.

Evidence firstCollect current state before changing it

Rollback awareKeep a verified route back

No credentialsNever paste passwords into a public checker

Inventory identities and data

List mailboxes, aliases, groups, shared folders, quotas, forwarding rules, calendars, contacts and client applications. Confirm which source credentials and protocols are available.

Prepare the destination

Create the accepted identities and quotas, validate login through IMAPS and submission, and publish required verification records without moving MX yet.

Run an initial copy

An initial IMAP sync reduces the final maintenance window. Compare folder counts and message totals, but remember that calendars, contacts and server-side rules may need a different migration method.

Cut over DNS and run the final delta

Lower TTL in advance. At cutover, change MX and related records, run a final sync, and verify SPF, DKIM, DMARC, TLS, incoming delivery and outgoing submission.

Keep the source for a defined period

Do not delete the source immediately. Monitor both queues and confirm user clients before closing the rollback window. Document when the destination became authoritative.