Project One Outlook – see how the new Outlook for Windows is different from its predecessor

Let’s see when the new Outlook for Windows becomes the default version and how it compares to the classic Outlook experience.

[Update]: The article was last updated on November 27, 2024. The new Outlook for Windows has reached Global Availability phase.

Over two years after the new Outlook for Windows preview was published, the tool becomes generally available. Let’s see how much it differs from the classic Outlook app. Is it the right time to switch from the classic Outlook for Windows experience? What’s in store for the near future? When will the new Outlook for Windows take over the classic desktop email client? Well, let’s read and find out (or at least try).

How to test the new Outlook for Windows

The new Outlook is currently in the Opt In phase. This means that, by default, you won’t be forced to switch to the new experience – you will have to actively choose to switch. There’s one, but I’ll get to that after describing the default behavior.

The Try the new Outlook toggle lets any Microsoft 365 user enable a separate (new) Outlook version. You can launch either version from the start menu. At first, both Outlook versions had the same name and the only quick way to distinguish them was to look at the icon: the new Outlook had the Pre text over it:

After that, the new Outlook got an upgrade. Instead of the Pre text, it said New, both on the icon and after the Outlook’s name. The icon’s design has also changed.

And now, that the new Outlook is officially out of the preview stage, it doesn’t have any annotation – it just states that it’s Outlook. Instead, as Microsoft announced, the classic Outlook gets the “classic” annotation, starting from version 2407:

The truth is, these icons vary from environment to environment. So, at the moment, you might see different icons for the same app on your PC.

New Outlook for Windows release roadmap

Here are some dates related to the Outlook Monarch project that let the new Outlook come into existence.

1. Back at Microsoft Ignite 2020, Microsoft unveiled some of the plans for making the Outlook client more uniform.
2. Then, the first materialization of those plans was Project Monarch – a leaked build of the popular email client. It emerged in May 2022 and shown a ‘pretty much OWA’ for desktop.
3. September 28, 2022: First release of the new Outlook for Windows for Office Insiders.
4. April 4, 2023: The new Outlook is available in Public Preview.
5. After the end of 2024, Mail, Calendar and People Apps on Windows 11 will become Outlook (the new Outlook). Honestly, I’m not sure if a whole lot of people will miss those, though. Now, the catch here is that Mail, Calendar and People Apps are free and the current Outlook for Windows is not. As a result, users without a paid Microsoft 365 subscription will have access to the new Outlook but with some ads displayed.
6. August 1, 2024: The new Outlook for Windows becomes generally available for commercial customers. The new Outlook for Windows is in the Opt In Phase, like it was during the preview.
7. Based on this article from the Outlook Blog, the next step will be the Opt Out phase. That’s when users will have to explicitly state they don’t want the new experience, instead of clicking “Try the new Outlook”.
   At Microsoft Ignite in 2024, during the Outlook-focused session, we learned that that the Opt Out phase will come in two waves. In 2025, its rollout will start for Small and Medium Business customers (B SKU), while the rollout for Enterprise (E SKU) is planned for mid 2026.We’re supposed to get a minimum of 12 months’ notice before it happens.
8. The final step will be a complete cutover, with no coming back to the “old Outlook”. At the moment, Microsoft states that the classic Outlook experience will be available at least until the planned support timeline, which is currently 2029.

Forcing the new Outlook

While we’re currently in the Opt In phase, there is a way to speed things up in your organization and force end users to switch to the new experience. The Admin-Controlled Migration to New Outlook policy is a Group Policy (or Cloud Policy) setting that allows admins to make users migrate to the new Outlook for Windows. This policy can either encourage users to test the new Outlook with a popup message or force the switch. After the admin-controlled migration, users still have the option to go back to the classic experience.

When to switch?

The project One Outlook (Outlook Monarch) makes a lot of sense. Instead of providing different Outlook experience on each platform, which must take a lot of Microsoft dev teams’ resources, the app will (eventually) offer unified looks, and users will have a single place for keeping their settings.

So, the crucial question for now is when to try the new Outlook for Windows: now, soon, or wait until it’s no longer a choice? To get a clear picture, let’s have a look at the most notable differences.

How is the new Outlook for Windows different?

Basically, it’s Outlook on the web (OWA), but on desktop. The resemblance is undeniable. Still, the looks and feeling are but a small part of the changes introduced to the new Outlook. Below are some important differences between the new Outlook and the old one:

Removed features

• COM add-ins won’t work anymore. The new Outlook for Windows supports only web-based add-ins. It’s not necessarily a bad thing, because many COM add-ins are performance-challenged. However, historically, there have been some useful add-ins that will not work in the new experience. It’s a good idea to look at what you’re using and find some replacements.
• No more relying on Outlook profiles (Control panel > Mail > Profiles). Outlook profiles let you easily switch between different settings, especially useful for demo environments. On the other hand, without Outlook profiles, there’s no need to recreate them, for example after a migration.
• At first, there was no support for OST & PST files. For some people, it made no difference. However, PST files have been used as a makeshift method (an unrecommended and not-too-reliable one, if I may add) of mailbox backup or migration. With the new Outlook, it’s not possible at the moment. But it seems there must have been some pressure from customers, since there are now plans to add PST support after all – the feature ID 399467 should have its rollout started in January 2025. At first, the new Outlook will provide read-only access to Mail items in PST files, but Microsoft plans to expand support capabilities in the future.
• No support for Exchange on-premises (at least not yet in April 2024).
• Initially, no support for POP & IMAP, but it’s reintroduced to new Outlook for Windows in May 2024.

Changed features

• Outlook settings moved from File > Options to Settings. That’s inherited from Outlook on the web, as well. If you’re used to the old way of setting up your Outlook, the switch might take some getting used to. Here’s a quick look at both settings windows:

• The ’old‘ Outlook allows you to cache chosen mailbox content locally and work with it while being offline. The cache works miracles when it comes to speeding up search, discovery and opening items. At the same time, it can really eat up storage on your device. The new Outlook’s equivalent for cache is its “offline settings”. While it doesn’t offer the same flexibility as  the classic Outlook’s cache, it still allows some offline work. By default, the new Outlook it saves the last 7 days of emails to your device, and the maximum limit is 180 days.
• Signature settings are in the cloud. While this is not a shocker after Microsoft introduced signature cloud settings, it is an important change – in the new Outlook, there’s no way back to use local email signatures. If you have some problems (like missing email signatures) after the switch, see how to solve them in this article.
• In the new Outlook, you can Save emails to the EML format only. The old one supported saving emails to: MSG, TXT, HTML, OFT and MHT formats. The good news is, since March 2024, you should be able to open EML, OFT and MSG files in the new Outlook, so there’s some progress.
• Outlook rules – some of the actions known from the old Outlook for Windows are no longer available, including: have server reply with a message, reply using a template, flag, clear flag, clear categories, play a (custom) sound, print, apply retention policy and display a desktop alert.

New features

• Easy access to Microsoft To Do, Viva Engage (Yammer), Bookings, OneDrive and the rest of the Office suite (Word, Excel, OneNote, PowerPoint) from the side pane.
• Modern architecture is supposed to shorten the time required to deliver fixes and new features to end users.
• Pinning, snoozing and scheduling emails.
• Loop components (elements that allow real-time collaboration directly in emails). Now that’s an interesting point. Loop components were one of the selling points of the new Outlook for Windows, but it turns out they were introduced in the classic Outlook for Windows as well (and work just as fine).
• Interaction with Microsoft 365 Copilot directly from the new Outlook (added in April 2024).
• AI-generated Outlook themes. These are supposed to give you the ability to personalize Outlook as you see fit. You can adjust your Outlook’s background to your mood, location, or anything you like.

Here is some more information on the new Outlook:

Things to know about the new Outlook for Windows

CodeTwo vs. the new Outlook

CodeTwo Email Signatures 365 (our email branding management tool) supports both the classic Outlook and the new Outlook. Our modern Web Add-in was featured on Microsoft Build as one of the best examples on how to use the possibilities offered by the new Outlook (and API related to it).

However, if you’re still using any of our freeware COM add-ins (some of them were popular back in the day!), it’s time to wave them goodbye. The new Outlook for Windows offers no way to support COM add-ins.

New Outlook for Windows – features roadmap

At the moment, the Try the new Outlook button encourages users to check out the new experience. While it’s still in the Opt In phase, the general availability is a huge milestone. It means that we’re dealing with a product that received a lot of feedback and had numerous bugs fixed. Microsoft is still collecting feedback and coming up with new features even as you read this. And to see that the developers behind the new Outlook are quite busy, you can take a look at the roadmap, filtering results by:

• “new Outlook for Windows” or
• #newoutlookforwindows

The list is extensive. The most recent ones that caught my attention are:

• S/MIME support. One of the most popular digital signing and encryption methods has already been available in Outlook on the web and in the classic Outlook. Starting from January 2025, it should be supported in the new Outlook as well.
• Newsletters – that’s a brand-new thing. The new Outlook will enable users to create and distribute internal email newsletters. It is said to include analytics to track internal campaigns’ performance. Rollout will start in November 2025.
• Drag and drop to download attachments and emails. Again – a heavily used feature known from the classic Outlook. Rollout start planned for December 2024.
• ICS support – the lack of this feature baffled users around the globe. Support for ICS files simplifies event and calendar management and was introduced in the new Outlook in September 2023.
• Conditional formatting – first introduced with the classic Microsoft Outlook 2010, this feature made its way back to the new Outlook in 2024.Advanced Mail Merge – a feature that offers some wonderful automation right from your email client. It’s planned for release in April 2025.Adding shared folders to Favorites. It doesn’t sound groundbreaking, but it’s another classic Outlook feature that many users have been missing.
• Inserting signatures into calendar events. Rollout planned for December 2024.

Now, for me, it’s reassuring to know that Microsoft is finding a way to reintroduce well-known and extensively used features that initially were missing from the new Outlook for Windows preview (like conditional formatting, PST support, offline mode and more). When looking at the snarkiest comments about “One Outlook”, the “missing features” section is the recurrent theme.

And now for the section that made (at least for a while) the new Outlook for Windows unusable to me. I ran across a problem that didn’t let me sign in to the new Outlook for Windows and I’ll show you how I managed to fix it.

Troubleshooting – Something went wrong when launching the new Outlook for Windows

Problem description

When you launch the new Outlook for Windows, you see a prompt to sign in. The sign-in attempt ends with the error message:

Something went wrong

We ran into an error – Error: GlobalSettingsAccountLogonFailed

or similar.

Solution

Go to your local AppData folder (C:\Users\YourUserName\AppData\Local\Microsoft) and delete the Olk folder. If it doesn’t help, delete the OneAuth folder, too. Try running the new Outlook for Windows again.

Background

It took me much more time than I’d like to admit to fix this problem.

When first trying to launch the new Outlook for Windows in a lab environment, Outlook wanted me to sign in with another user’s credentials. The problem was that the user’s account was long gone – neither the user nor their Microsoft 365 tenant existed any more. It didn’t prevent the user’s profile from being cached, though.

Unlike the standard sign-in prompt, this one didn’t let me sign in as another user. First attempt to close the sign-in window caused it to appear once again. The second one returned the LogonFailed error.

What I tried:

• Repairing and reinstalling the Office suite (Microsoft 365 Apps for Business).
• Clearing all the info in the Windows Credential Manager.
• Deleting & recreating all Outlook profiles.

None of these actions made any impact. The search for the cached profile location was the final step before dropping the ’format c‘ bomb on my lab environment.