Start with an inventory, not the admin portal

List every person, mailbox, alias, shared inbox, distribution group and forwarding rule. Record who owns each account, who still needs access and which addresses must continue receiving mail.

Do not assume the visible staff list is the whole system. Accounts such as accounts@, bookings@ or info@ may be connected to website forms, printers, donation services and suppliers.

  • Old and new email address
  • Display name and responsible person
  • Mailbox size and important folders
  • Aliases, delegates and forwarding
  • Required Microsoft 365 licence
  • Device or application dependencies

Protect access before the move

Confirm that the organisation controls the domain and can change its DNS. Use named administrator accounts, multi-factor authentication and a tested recovery route. Document the current MX, SPF, DKIM and DMARC records before altering them.

Decide how old data will be preserved and what must be retained for legal, financial or safeguarding reasons. A migration is not a substitute for an agreed backup and retention policy.

Pilot one ordinary mailbox

Choose a cooperative user whose mailbox represents normal use but is not business-critical. Test message history, folders, contacts, calendars, mobile sign-in, desktop Outlook and sending to external recipients.

Write down every exception. A successful login is not enough: verify that recent and old mail arrived, replies use the correct address and shared resources still work.

Plan the cutover and support window

Tell users when changes will happen, what they need to do and where they can get help. Keep the old service available until the new environment has been checked and signed off.

After changing mail-flow DNS, test inbound and outbound delivery from unrelated providers. Monitor rejected messages and authentication results. Only close the old service after the agreed verification period.

What the free planner does—and does not do

The London Community IT planner creates a practical checklist, provides a mailbox-mapping CSV and checks basic email formats and duplicates in your browser. It does not connect to a tenant, store credentials or move messages.

The actual migration still needs authorised administrator access, suitable licences, a supported migration method and someone responsible for recovery if the cutover does not behave as expected.