A migration from Exchange on-premises to Exchange Online pays off most when you also use the rest of Microsoft 365 afterwards, such as Teams, OneDrive and better security. This article lists the benefits for users and for IT, and how to approach the migration. With Exchange 2016 and 2019 out of support since October 2025, the choice has become more urgent: migrate to Exchange Online, or move to Exchange Server SE if you want to stay on-premises.
Benefits for users
- Bigger mailboxes: depending on your license you get much more storage than most on-premises environments offer, plus an online archive.
- Access everywhere: Outlook on Windows, Mac, the web and your phone, without VPN.
- Integration with Teams: calendars, meetings and email work seamlessly with Teams.
- Do more yourself: with self-service password reset, users reset their own password.
- Automate with Power Automate, for example saving attachments to OneDrive automatically.
- Copilot: with a Copilot license, AI helps summarize and draft emails.
Benefits for IT
- No more server patching: Microsoft keeps Exchange Online up to date. On-premises Exchange servers were a frequent attack target in recent years.
- Better security: MFA, Conditional Access and Microsoft Defender for Office 365 are easy to turn on.
- Lower total cost: no more hardware, storage, backups and server licenses. The cost is a fixed amount per user.
- Availability: Microsoft provides redundancy across multiple datacenters.
- Compliance: retention policies, eDiscovery and sensitivity labels via Microsoft Purview.
How do you approach the migration?
- Choose a method: a cutover for small organizations, a hybrid migration for most others.
- Pre-sync: with a hybrid migration you copy mailboxes to the cloud in advance, without user impact.
- Measure: how much data, what throughput, how much time. Add a margin for the unexpected.
- Communicate: tell everyone when the migration happens, but above all why and what they gain.
- Switch over at a chosen moment.
You find the full plan in the Exchange migration action plan.
What to watch out for
- Applications and printers that send through your on-premises Exchange need a new way to send.
- Old Outlook versions and protocols using basic authentication no longer work with Exchange Online.
- Permissions between mailboxes work best when those mailboxes move together.
Also see set Full Access and Send As permissions and block ActiveSync in Exchange Online.
Read also
Exchange migration to Microsoft 365: an action plan
Why and when to choose an Exchange hybrid
Enable multi-factor authentication (MFA) in Microsoft 365
Nederlandstalige versie: De voordelen van een Exchange-migratie naar Microsoft 365