Moving from Gmail or hosting mail to business email without downtime

No lost mail on the day and nobody without email for half a day: a step-by-step migration plan and five common mistakes.

Short answer: The secret of a migration without downtime is the order: first the new mailboxes are created and old mail is copied in the background, then the MX record is switched outside working hours, and finally the difference is collected in a second pass. Mail arriving on the day is not lost, and in the morning staff open their new mailbox with the same address.

Step-by-step plan

1. Inventory: list all accounts, aliases, forwards, shared addresses, mailbox sizes and the devices that send mail (printers, web forms, accounting software).
2. DNS preparation: shorten the MX record's TTL one day before the move so the change spreads within minutes.
3. New mailboxes: create users, aliases and shared mailboxes in Exchange Online with the same addresses; verify the domain.
4. First copy: old mail, folders, calendars and contacts are copied to the new mailboxes in the background while everyone keeps using the old system.
5. MX switch: outside working hours the MX record is pointed to Exchange Online; from then on new mail lands in the new mailbox.
6. Delta copy: mail that arrived in the old mailbox between the first copy and the MX switch is collected in a second pass.
7. Devices and records: Outlook and phones are connected to the new account; SPF, DKIM and DMARC records are updated for the new system.
8. Old account: the old mailboxes stay open read-only for a few weeks, then they are closed.

Five common mistakes

1. Switching MX before copying: staff find an empty mailbox in the morning and old mail is missing for days.
2. Forgetting aliases: mail sent to aliases such as sales@ bounces after the move.
3. Leaving two SPF records: more than one SPF record on a domain makes every message fail authentication; they must be merged into one.
4. Moving only the mail: hosting mail often keeps contacts and calendars separately; IMAP does not bring them over, so they must be transferred separately.
5. Forgetting printers and forms: a scan-to-email printer or your website's contact form keeps trying the old server settings and silently stops.

After the move

DMARC reports are monitored for a few weeks to see whether any other system sends mail in your name, and the policy is then moved gradually to enforcement. Your mail stays out of spam folders and nobody can send fake mail in your company's name.

How we help

We run the move from Gmail and Google Workspace, cPanel and hosting mail or legacy Exchange to Exchange Online or Microsoft 365 remotely from start to finish. Inventory, copy, out-of-hours MX switch, device setup and DNS security records are handled in one plan, wherever you are.