The differences that matter
| Exchange Server (SE) | Exchange Online | |
|---|---|---|
| Who runs the servers | You, or a hosting provider | Microsoft |
| Updates | Installed by whoever runs it | Applied by Microsoft |
| Licensing | Server licences and CALs, plus an active subscription | Per user, per month |
| Where the data lives | Wherever the servers are | Microsoft’s data centres for your region |
| Mailbox size | Set by the administrator | 50 GB (Plan 1) or 100 GB (Plan 2 and Microsoft 365 business plans) |
| New Outlook for Windows | Not supported | Supported |
| Classic Outlook, web, phones | Supported | Supported |
Where hosted Exchange fits
Hosted Exchange is Exchange Server run by a provider, so it sits in the left-hand column: you do not run the servers, but the platform is Exchange Server SE rather than Microsoft’s cloud. That is how providers like us can guarantee UK-only hosting and offer controls such as the SolidCP panel. The trade-off is the new Outlook for Windows, which only supports Exchange Online — classic Outlook works fully and is supported until at least 2029. Our guide to the new Outlook explains.
If you are deciding whether to run Exchange Server yourself, our guide to Exchange Server SE costs and licensing sets out what it involves.