Move email with a mailbox inventory and a verification plan

Moving a domain's email involves more than changing one DNS record. Existing messages, aliases, client settings and website senders can all depend on the old service.

Start with an inventory so the move has a clear completion test.

List what actually exists

Record mailboxes, aliases, forwarding rules and applications that send mail. Note which users need historical messages and how they currently access them.

Do not collect everyone's passwords in a shared spreadsheet. Use the migration and access procedures appropriate to the source and destination services.

Prepare the destination first

Create the required accounts and verify login through the destination's supported interface. Test sending and receiving with the service's documented configuration before changing public delivery.

Record the new client settings and authentication records. A mailbox that can receive messages may still have an incorrectly configured outgoing SMTP connection.

Plan the message transfer

Decide how historical folders and messages will be copied and how you will check the result. Compare representative folders, recent messages and attachments rather than relying only on a total item count.

Keep the old service available for the agreed transition period where practical. Late-arriving messages or a device still using old settings may otherwise be missed.

Verify after the DNS change

Test delivery from an outside address, sending to an outside recipient and replies. Check each important application that uses the domain for notifications or contact forms.

If a user reports missing mail, ask which address, folder and time window are involved. That is more actionable than a general statement that the migration failed.

Use the DNS verification checklist, mail client guide and SMTP guide to cover the separate parts of the move.