Microsoft’s New Outlook is here — combining desktop, web, and mobile experiences into a single unified platform. If your organization is mid-transition, or you’re wondering what it means for your Outlook add-ins and email workflows, here’s what you need to know.
This post breaks down what changed, what stayed the same, and how harmon.ie works in the new Outlook environment.
At harmon.ie, we’ve been extending Outlook for over a decade and have been working with the new Outlook extensibility model since early availability. Here’s what the transition means in practice.
What is New Outlook, and why did Microsoft build it?
What started as “One Outlook” during development was renamed “New Outlook” at launch, and has since been rebranded simply as “Outlook” — with the previous version now called “Outlook (classic).” You may see all three names used; they all refer to the same modern, unified platform.
Until recently, Microsoft maintained separate Outlook apps for different platforms — a decades-long approach where mobile apps and web-based Outlook experiences each had their own codebase, separate from the Windows and macOS desktop clients.
The One Outlook strategy changes that: instead of maintaining and improving multiple apps, Microsoft consolidated them into a single app with a single codebase that runs everywhere. Classic Outlook for Windows is still supported during the transition, but New Outlook is now the default for Microsoft 365 users — not sure when to make the move? We’ve covered that too.
What does this mean for end users?
First and foremost, the refreshed Outlook UX/UI looks and functions the same way on all platforms. This consistency slashes the learning curve and frustration with shifting from one experience to the next.
New Outlook is essentially the Outlook Web experience, now available as the desktop client. It has all the things the browser version of Outlook has had for a while: a calendar board view to organize your day; tasks, meetings, notes, and links visible on a board; and the ability to pin messages to the top of your inbox, snooze them, and drag them to your To-Do list.
A number of additions make New Outlook a more customizable and native desktop experience — a configurable ribbon, embedded window controls, new windows when you compose a message or create a calendar event, message reminders, and support for Loop components.
Microsoft has brought the best of Outlook Web together with the features that make a desktop client feel native to the OS.
For a full feature comparison, see our New Outlook vs. Old Outlook guide.
What does this mean for IT teams?
Providing internal support for Outlook gets a lot easier once everyone is on New Outlook. A consistent user experience means simpler training and the ability to support internal users regardless of what device they’re using.
New Outlook’s web-first strategy also means local device issues are less likely, as most computing and storage occurs in the cloud. After the initial bumpiness of the transition, users need less individualized Outlook support — and when tickets do come in, there’s a shorter path to resolution since everyone has the same UX and configuration.
New Outlook introduced a new extensibility model, which means older COM-based Outlook plug-ins don’t work in the new interface and need to be replaced. The new model enables third parties to develop Outlook add-ins similar to Teams Apps. For a full breakdown of add-ins and the new Outlook — including which ones are compatible and what to do about the ones that aren’t — we’ve covered it in depth. New harmon.ie is already built on this model — no compatibility work required.
Will we still be able to use harmon.ie?
Yes — and harmon.ie is better positioned for New Outlook than most add-ins.
New harmon.ie is a modern web add-in built specifically for the new Outlook extensibility model. It works in:
- Outlook for Windows (new Outlook interface)
- Outlook (Classic)
- Outlook for Mac
- Outlook on the Web
Unlike older COM add-ins that require local installation and break in New Outlook, New harmon.ie is deployed centrally through Microsoft 365 or Intune and updates automatically. End users don’t install anything.
Everything you rely on today — saving emails to SharePoint, attaching files from Teams, mapping email headers to SharePoint metadata — works in New Outlook without changes. harmon.ie is already trusted by 1,600+ organizations for exactly this reason.
If your organization is evaluating its add-in stack ahead of the New Outlook transition, start a free 21-day trial — no credit card required. Or book a demo to see it running in your Outlook environment.
