How to move your email off Google Workspace or Microsoft 365

Write down every mailbox, alias, shared address, forwarding rule and distribution group, and roughly how much mail each mailbox holds. Note every other service that sends as your domain, such as invoicing or newsletters, because their DNS records must survive the move.

• Lower the TTL of your MX records to five minutes, 24 to 48 hours before the switch, so the change takes effect quickly.
• Set up SPF, DKIM and DMARC for the new provider in advance. Keep the old provider in SPF until the switch is done.

Create the new mailboxes, then copy every folder from the old account while people keep working. The standard tool for this is imapsync, which copies server to server and can run again later to pick up only what is new.

• Microsoft 365 no longer accepts plain passwords for IMAP. The copy needs an OAuth app registration in your Microsoft tenant.
• Google Workspace needs IMAP turned on, and an app password or OAuth for each account.

At a quiet hour, point your MX records to the new provider. New mail starts arriving there within minutes. Then run the copy once more to pick up anything that landed in the old account in between.

1. Set up mail apps on phones and laptops with the new server settings.
2. Keep the old account for two to four weeks as a fallback, with forwarding to the new address.
3. Export calendars (ICS) and contacts (VCF) separately; they do not travel over IMAP.
4. Remove the old provider from SPF, and only then cancel the subscription.
5. Run a mail check to confirm SPF, DKIM, DMARC and TLS on the new setup.