What to expect from a Microsoft 365 migration
A Microsoft 365 migration needs an inventory, access plan, test, changeover and handover. Check the scope before agreeing on timing.
Read the short answer
The short answer
A Microsoft 365 migration should specify which email and files move, how accounts and devices change, and how the result will be tested. Confirm domain access, source data and limitations before setting the changeover date.
List the data and accounts
Include individual mailboxes, shared addresses, calendars, contacts and shared files. Check whether people also hold local archives or business data outside the current cloud service. Those records may need separate work.
Document what is included and what remains available in the old system. A mailbox count alone is not a complete migration scope.
Establish the required access
The project needs appropriate access to the source, destination and domain. Identify the business owner of each service and the recovery process. Avoid sharing administrator passwords in ordinary email or an enquiry form.
Prepare the destination accounts and licences before moving data. Check the apps and devices people will use after the switch.
Test a representative sample
A sample should reflect the data and permissions people actually use. Check messages, calendars and shared access where they are included. Use the findings to confirm the approach and communicate limits.
A successful small test reduces uncertainty but does not remove every migration risk. Keep the recovery and transition plan explicit.
Plan the changeover communication
Staff need to know when to stop changing settings, which account to use and where to ask for help. The domain change should account for website forms and other systems that send mail.
Verify sending and receiving after the switch. Keep a list of issues and owners rather than asking everyone to make unrelated changes at once.
Close with evidence and a handover
Check the agreed data, devices and shared tasks. Record any exclusions, outstanding work and the point at which the old service can be retired. The business should retain administrator and subscription details.
Discuss likely disruption before agreeing on a date. A promise of zero downtime is not a substitute for a workable migration and recovery plan.
Does moving email also move calendars and contacts?
That depends on the source and the migration method. Microsoft documents different routes for different environments, and some methods have narrower coverage than others. Confirm calendars, contacts, permissions and local archives explicitly rather than assuming everything travels with the inbox.
For each record type, identify a sample and the check that proves the agreed result. A mailbox containing old messages does not establish that a shared calendar or contact list is available to the people who need it.
What belongs in the changeover checklist?
Record the person approving the switch, the relevant domain settings and the order of the tasks. Include mail sent by the website, accounting software and other business systems. Confirm incoming and outgoing messages with a safe test after the change.
Keep an issue list during the transition with the user, symptom, time and next action. Agree on the point at which old subscriptions can be cancelled. Retiring the source is a separate decision after the agreed data and daily work have been checked.
Sources and further reading
These links take you to the publisher's guidance. Product details and requirements can change, so check the current source before making a change.
Content reviewed on 7 October 2026. This guide is a starting point. The scope of a support job depends on your systems, access and business requirements.