1. Make a list before you move anything
- Every mailbox, including people who left but whose mail you must keep.
- Shared addresses such as info@ or office@, aliases, groups and forwarding rules.
- Who controls your domain registrar and DNS, and that you can sign in today.
- Calendars, contacts and any mail archives on individual computers.
- Apps and devices that send email, such as copiers, websites and event or sign-up forms.
2. From Google Workspace to Microsoft 365
Microsoft documents a batch migration tool in the Exchange admin center that moves email, contacts and calendars from Google Workspace. Microsoft says you can keep both systems active and move groups of users over time.
The prerequisites matter: Microsoft's steps include creating subdomains for mail routing in both directions, preparing the destination mailboxes, and having a Google Workspace super administrator authorize access. Follow them in order.
Sources: Microsoft: migrate email and calendar from Google Workspace; Microsoft: Google Workspace migration prerequisites
3. From another host that supports IMAP
If your mail sits with a hosting company or webmail provider, Microsoft supports IMAP migration into Microsoft 365 when the source system supports IMAP. IMAP moves email only, so plan to move calendars and contacts separately.
Source: Microsoft: migrating IMAP mailboxes to Microsoft 365
4. From Microsoft 365 or IMAP to Google Workspace
Google's data import tool, in the Google Admin console, copies email from Exchange Online, IMAP webmail providers, another Workspace account or a personal Gmail account. A super administrator runs it.
Source: Google Workspace: import email with the data import tool
5. Switch mail flow and protect your domain
- Lower the DNS time-to-live on your MX record a day or two before the switch.
- Change the MX record to the new system once mailboxes are synced.
- Update SPF, turn on DKIM and publish a DMARC record for the new system.
- Keep the old system running until mail stops arriving there, then run a final sync.
- Turn on multi-factor sign-in for every new account on day one.
Help from the vendors
Microsoft lists FastTrack for Microsoft 365 migration guidance at no additional cost for eligible nonprofit customers. Check the page for current terms.
Common questions
Will we lose email during the move?
Not if both systems stay active until the final sync. Mail keeps arriving in the old system until the MX record changes, and the migration tools copy it across.
How long does a small nonprofit migration take?
It depends on the number of mailboxes and how much mail they hold. Microsoft notes that batch time depends on how many users you move. Planning and DNS access often take longer than the copy itself.
Can we move only some people first?
Yes. Microsoft's Google Workspace tool is designed to move groups of users over time while both systems stay active.