Moving company email to Microsoft 365 or Google Workspace is mostly a copying job, and copying is the part that rarely goes wrong. Problems come from everything around it: an alias nobody listed, a scanner that still sends through the old server, a DNS record changed too early. This email migration checklist follows the order in which a small or mid-sized business should work, from the inventory to the week after the switch, so the first Monday on the new platform is uneventful.

Step 1: the email migration checklist starts with an inventory

Before you pick a date, write down everything that sends or receives mail under your domain:

  • Every user mailbox, with its approximate size.
  • Aliases, shared addresses such as info@ or billing@, distribution lists and forwarding rules.
  • Shared calendars, room calendars and delegated access between mailboxes.
  • Devices and services that send mail: copiers and scanners, the website contact form, invoicing or CRM software, alarm panels.
  • Local archives, such as PST files kept on individual computers.
  • Where your DNS is hosted and who can log in to it.

Also note who holds admin access to the current system. With an admin account the migration tools can read every mailbox without collecting staff passwords. The same list is what we ask for before an email migration to Microsoft 365 or Google Workspace.

Step 2: choose how the mail will move

To migrate email to Microsoft 365, Microsoft documents several routes in its guide to migrating mailboxes:

  • Cutover migration from an Exchange server, which moves mail, calendars and contacts. Microsoft allows up to 2,000 mailboxes this way but calls 150 or fewer the more reasonable size.
  • IMAP migration from web hosts and other IMAP systems. It copies mail folders only; contacts, calendars and tasks have to be moved separately. Microsoft lists limits of 500,000 items per mailbox and 35 MB for the largest message.
  • Google Workspace migration from Gmail in Google Workspace, which can bring over mail, calendars and contacts.
  • PST import through Microsoft's Import Service, when a lot of older mail lives in PST files.

To migrate email to Google Workspace, Google's data import tool in the Admin console copies email, calendars and contacts from Exchange Online, and email from IMAP providers. In either direction, a move away from a web host's mailboxes is the most common case for small businesses, and it is the one where contacts and calendars are most often forgotten.

Step 3: prepare DNS before the switch

A day or two before the cutover, lower the DNS TTL on your MX records, for example to a few minutes. The TTL tells other servers how long they may keep using the old answer; a short value means the change takes effect quickly and can be reversed quickly. While you are in the DNS panel, add the verification record the new provider asks for, so it can confirm you own the domain.

On the night itself, change MX records to the values the new provider gives you and remove the old ones. Leaving old and new MX entries side by side splits incoming mail between two systems. If you are moving to Microsoft 365, add the autodiscover record as well; Outlook uses it to find the new mailbox without manual server settings.

Step 4: SPF, DKIM and DMARC on the new platform

Mail authentication decides whether your messages reach the inbox or the spam folder. Gmail's email sender guidelines require every sender to use SPF or DKIM, and bulk senders to use SPF, DKIM and DMARC.

  • SPF record. A domain may publish only one SPF record. Merge the new provider into it together with every other service that sends as your domain, and stay within the ten DNS lookups the SPF standard allows.
  • DKIM signing. Turn on DKIM signing in the new admin console and publish the keys it generates. Microsoft 365 uses two CNAME records; Google Workspace gives you a TXT record.
  • DMARC policy. Start with a monitoring policy (p=none) and a reporting address, read the reports for a few weeks, then move to quarantine or reject once every legitimate sender passes.

If the DNS for your domain is spread across a registrar, a web host and a former IT provider, sort it out first; our DNS configuration and management service handles records like these.

Step 5: cutover day and the week after

  1. Copy older mail in the background during the days before the switch, so only recent messages remain to be moved.
  2. Change the MX records, then run a final sync to catch messages that reached the old server in between.
  3. Connect Outlook, phones and tablets to the new accounts, and recreate inbox rules, signatures and shared calendars.
  4. Send a test message from each copier, form and application you listed in step 1.
  5. Keep the old service active for a while and check it for stray messages before cancelling it.
  6. Set up a backup for the new mailboxes, since cloud platforms keep deleted items only for a limited time.

Frequently asked questions: email migration checklist

How long does email migration take?

It depends on the number and size of the mailboxes and on how fast the old server lets data out. Because older mail is copied before the switch, the cutover itself can happen in an evening, while the background copy of years of mail may run for days.

Will we lose any email when we change providers?

Not if the move is planned: copy first, change the MX records, sync again and compare item counts folder by folder. The usual gaps are PST files on individual computers and the contacts and calendars that an IMAP migration leaves behind.

Will our scanners and website forms keep sending mail?

Only after they are reconfigured. Devices that send through the old server need the new provider's settings, and older equipment that signs in with a plain username and password may need a relay or another sending method, because Microsoft and Google have been phasing out that kind of sign-in. Check the current vendor documentation for your model.

Planning a move for an office in Los Angeles or Long Beach? Our professional email migration service covers the background copy, the MX cutover, the final sweep and device setup. Decide early how the new mailboxes will be backed up; our backup and disaster recovery page explains the options. Contact us with the number of users, where your email is hosted today and the platform you are moving to.