New Outlook vs classic Outlook on Windows
Microsoft is replacing the classic Outlook for Windows with a web-based "new Outlook." Here's what changes.
For two decades, "Outlook for Windows" meant the classic Win32 application built on a long lineage. In 2024, Microsoft began rolling out the new Outlook for Windows, a web-based client that shares its codebase with Outlook on the web (OWA) and the new Outlook for Mac. Knowing what's the same and what's not avoids unhappy surprises.
What the new Outlook is
The new Outlook is the OWA codebase running inside a desktop wrapper. It looks, feels, and updates like the web client — same UI conventions, same features ship at the same time. It connects to Exchange Online via Microsoft Graph APIs rather than the older MAPI/RPC channel.
What the new Outlook is good at
- Faster feature rollout — new features arrive on the new client first.
- Better integration with Microsoft 365 Copilot, Loop, and Teams.
- Modern profile management with multiple accounts (work and personal) in a single app.
- Lighter resource use for typical mailbox sizes.
- Familiar OWA experience for users who already lived there.
What it doesn't yet do (in 2026)
The new Outlook is now feature-parity with classic Outlook for most users, but a few gaps remain depending on workload:
- Some COM add-ins are still classic-only; the new Outlook supports web add-ins via Office.js.
- Local PST/OST files — handling is changing; classic Outlook still has more flexibility.
- Macro and VBA support — classic only.
- Some shared mailbox edge cases behave differently.
- POP and IMAP account support was late to ship.
For users with deep classic-Outlook customisations (rules, signature templates, third-party COM add-ins), the gap can still be material.
How Microsoft is rolling it out
The new Outlook is enabled by default for new Microsoft 365 users. Existing users get a toggle in classic Outlook to "Try the new Outlook." IT can pin or pre-deploy either client via Intune and the Office Deployment Tool. Microsoft has stated the long-term direction is the new Outlook everywhere — but classic remains supported on a defined timeline.
What admins should do
- Inventory classic-only dependencies (COM add-ins, VBA, PSTs, certain shared-mailbox workflows).
- Run a pilot with knowledge workers, then expand.
- Set Outlook deployment policies in Intune to control which clients show up.
- Communicate the change clearly — many users find the UI different enough to need a heads-up.
For most users in 2026, the new Outlook is now the right default. Just don't migrate everyone on the same day.