Microsoft 365 to Switch Users to New Outlook

Microsoft 365 to Switch Users to New Outlook in 2025

Microsoft has confirmed that the classic Outlook for Windows app will be retired and replaced by the new Outlook for all Microsoft 365 commercial users during 2025.

If your business uses Outlook, this change will affect your team. Here's what you need to know. You may also want to read about the broader changes coming to Microsoft 365 — including how Copilot Agents are transforming workflows.

What's Changing?

The classic Outlook desktop app (the one most businesses have used for years) is being replaced by a new, web-based version. This new Outlook looks and feels more like Outlook on the web, with a modernised interface and tighter integration with other Microsoft 365 services.

Microsoft has been rolling out the new Outlook gradually, but from 2025, the switch will become mandatory for Microsoft 365 Business and Enterprise users.

What's Different in the New Outlook?

The new Outlook includes several changes:

• Modernised interface: A cleaner, more consistent design that matches the web version of Outlook.

• Integrated apps: Access to Microsoft Teams, To Do, and Calendar directly from the Outlook sidebar.

• AI features: Copilot integration for email summarisation, drafting, and scheduling (requires Copilot licence). For more on this, see Jay's Introduction to Microsoft Copilot 365.

• Faster updates: As a web-based app, new features are delivered faster without waiting for desktop update cycles.

What's Being Removed or Changed?

Some features from classic Outlook may not be available in the new version initially:

• Offline access: The new Outlook has offline capabilities, but they work differently from the classic app.

• COM add-ins: If your business uses custom Outlook add-ins, they may need to be updated or replaced with web-based equivalents.

• PST file management: Handling local PST files is more limited in the new version.

• Multiple account support: The new Outlook supports multiple accounts, but the experience is different from classic Outlook.

Microsoft continues to add features to the new Outlook, so the gap between the two versions is closing with each update.

Watch the Overview

We've put together a short video explaining the key changes and what your business should do to prepare:

What Should You Do Now?

• Test the new Outlook: Encourage a small group of users to try the new Outlook and report any issues or missing features.

• Check your add-ins: If your team uses Outlook add-ins, verify they're compatible with the new version.

• Plan the transition: Don't wait for the forced switch – a planned rollout is always smoother than a last-minute scramble.

• Communicate with your team: Let your staff know the change is coming and provide guidance on what to expect.

How Flotek Can Help

If you'd like help preparing for the switch, or if you want us to test compatibility for your organisation, get in touch with our team. We can help with testing, deployment planning, and user training to make the transition as smooth as possible.

Further reading: 16 Benefits Of Microsoft 365 | What Is Microsoft Copilot

Discover how Flotek can help with our Microsoft 365 solutions. Get in touch today.

Further Reading

Jay's Introduction to Microsoft Copilot 365 — understand how Copilot works within the new Outlook and across Microsoft 365.

Microsoft Teams Updates | April Edition — more changes coming to the Microsoft 365 suite this spring.

Microsoft 365 Copilot for Small Businesses — Copilot Business is now available for organisations under 300 users.

Flotek Microsoft 365 Solutions — deployment, licensing, and ongoing support from Flotek.

Copilot Webinar Recording: Catch Up Now! — see how Copilot works inside Outlook with live demos.