Glossary · Mailboxes
Email migration is moving mailboxes, existing mail and DNS from one email provider to another without losing messages.
The usual order: create the mailboxes at the new provider, copy existing mail across with IMAP import, lower the DNS TTL, then switch the MX records and update SPF, DKIM and DMARC for the new sender.
Keep the old account for a week or two after the switch: a few messages arrive late from servers that cached the old MX, and people will need time to reconnect their mail apps.
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