Plan before you move

List mailboxes, shared mailboxes, aliases, devices and apps that use email. Decide the migration method and cut-over date.

Prepare the tenant

Create users and licences, add your domain, set up MFA and decide security settings before anyone is migrated.

Handle DNS carefully

Lower DNS record lifetimes in advance so the switch of mail routing takes effect quickly, and document the existing records first.

Migrate in stages

Move mail in batches, with the bulk of historic data copied before cut-over. Keep mail flowing throughout.

Update devices

Re-connect Outlook and mobile devices, and check shared mailboxes, calendars and permissions.

After go-live

Check mail flow and spam filtering, retire the old system once you are confident and review licences after a few weeks.