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Exchange to Microsoft 365 migration

Led the move from an on-premise Exchange server to Exchange Online in Microsoft 365.

Migration path

flow
  1. InventoryMailbox readiness
  2. License mappingUsers and plans
  3. DNS & cutoverPlanned window
  4. Identity securityMFA and access policy
  5. User onboardingOutlook and mobile

The problem

Email ran on an on-premise Exchange server. That meant server hardware to maintain, patching and backups handled in-house, and limited access for staff working outside the office.

The approach

  • Planned the migration: mailbox inventory, licence mapping, and DNS changes (MX, Autodiscover, SPF/DKIM/DMARC).
  • Ran a cutover migration outside working hours, so people kept working through the move.
  • Turned on MFA and Conditional Access in Azure AD from day one.
  • Helped staff with first sign-in and with Outlook and mobile setup.

The result

Around 500 mailboxes moved to Exchange Online over a single weekend, with roughly four hours of downtime outside working hours. The on-premise server was retired, so mail patching and backups are no longer ours to run.

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