Inside the new Outlook for Windows – key changes, dates, and features

The new Outlook for Windows is now generally available and is starting to be rolled out as the default version. Let’s see how much it differs from the classic Outlook. I’ll also try to answer the most common questions about the new Outlook, like:

Is now the right time to switch? How to switch between versions? What’s new? When will the new Outlook for Windows be the default option for my company?

Well, dive into the article and find out! (Or at least try.)

What is the new Outlook for Windows?

The new Outlook for Windows is the latest version of one of the most popular email clients. It’s a blend of the classic Outlook for Windows and Outlook on the web. It’s still installed on your PC, but it’s clear that its UI is based on the web version.

The new Outlook for Windows has been evolving ever since its first preview appeared back in 2022. Even its icon has changed a few times since then. Here’s how the new Outlook for Windows icon has evolved from its first version up to now:

How to switch to the new Outlook for Windows?

If you still use the classic Outlook, you need to click the Try the new Outlook toggle in the top-right corner to switch to the new Outlook experience:

When you enable the toggle, the new Outlook version will become available to you and will be set as your default Outlook app. Afterwards, even if you select the classic Outlook from the Start menu, the new Outlook will open.

If you use Outlook in an Enterprise environment, this is the standard workflow – the classic Outlook remains the default version until March 2027, and you need to actively use the Try the new Outlook toggle to switch to the new experience.

However, for small and medium-sized companies, the new Outlook is now in the Opt Out phase. This means that the new experience is the default one for such organizations (with no need to use the toggle), but you can still switch back to the classic Outlook, if you want.

How can I switch back to the classic Outlook?

To switch back (or simply use the classic Outlook without setting it as the default app again), you need to disable the New Outlook toggle in the top-right corner of the new version. Disabling the toggle minimizes the new Outlook for Windows and opens the classic version instead.

Additionally, if your PC came without the classic Outlook preinstalled, using the switch button should install the classic version and then switch you to it. But that’s only in theory. In practice, the button doesn’t work that way (at least at the time I write this). You need to install the classic app yourself before attempting to switch.

New Outlook for Windows release roadmap

Here are some dates related to the release of the new Outlook for Windows, starting from the first mentions and ending with the date it completely takes over.

1. Back at Microsoft Ignite 2020, Microsoft unveils some of the plans for making the Outlook client more uniform.
2. Then, the first materialization of those plans is Project Monarch – a leaked build of the popular email client. It emerges in May 2022 and is a ‘pretty much OWA for desktop’.
3. September 28, 2022: First release of the new Outlook for Windows for Office Insiders (fancy name for the beta tester program).
4. April 4, 2023: The new Outlook becomes available in Public Preview.
5. 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.
6. On December 31, 2024, Mail, Calendar and People Apps are no longer supported. On Windows 11, those apps are automatically replaced by 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, while 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.
7. February 2025: While seemingly nothing changes, the new Outlook gets force-installed via Windows Update with no way to block Windows from preinstalling it. Before that, the new Outlook was installed after the user had chosen to try it. The new approach makes sense, since the new Outlook will be the default one in the future. Why not download and install it beforehand, right?
8. The next step is the Opt Out phase. That’s when users have to explicitly state they don’t want the new experience, instead of clicking “Try the new Outlook”.
   In 2025, its rollout starts for users with Microsoft 365 Business Standard and Premium licenses, while the rollout for Enterprise license users is currently postponed to March 2027 (previously April 2026). This rollout happens automatically, still allowing users to switch back to the classic Outlook.
9. 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

If the rollout of the new Outlook hasn’t yet taken place in your organization, but you want to force end users to switch to the new experience, there is a way to speed things up. The Policy for Admin-Controlled Migration to new Outlook for Windows 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 idea of unifying different Outlook versions into the new Outlook app (formerly known as One Outlook or Project Monarch) makes a lot of sense. Instead of providing a different Outlook experience on each platform, which likely takes a lot of Microsoft dev teams’ resources, the new app will (eventually) offer unified looks and a single place for users to keep 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 don’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 support for Outlook profiles (accessible in the classic Outlook via File > Account Settings > Manage Profiles). As long as they are available in the classic experience, Outlook profiles let you easily switch between different settings, which is especially useful for demo environments. While the new version doesn’t allow you to create separate profiles or migrate them, you can still use multiple accounts within a single profile.
• At first, the new Outlook wasn’t supposed to support 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 and there must have been some pressure from customers, since it’s now possible to export an entire mailbox or a specific mailbox folder to a PST file. There are also plans to extend PST support even further, including the option to import PST files to a mailbox, which is scheduled to roll out starting in April 2026.
• No support for Exchange on-premises (at least not yet in early 2026).
• Limited support for POP & IMAP. In theory, the feature enabling users to add IMAP and POP accounts was reintroduced in May 2024 and is still referenced in the account setup wizard, but users have reported various issues when configuring such accounts in the new Outlook for Windows. If you have an IMAP/POP account, you’ll probably want to keep using the classic Outlook.

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” (Settings > General > Offline). While these settings don’t offer the same flexibility as the classic Outlook’s cache, they still allow some offline work. By default, the new Outlook saves the last 7 days of emails to your device, and the maximum limit is 180 days. And starting from May 2025, this became even more useful with the ability to open attachments while offline.
• 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 as EML and MSG files only. The classic one supported saving emails to MSG, TXT, HTML, OFT and MHT formats. Since March 2024, you can open EML, OFT and MSG files in the new Outlook, but the other formats are not supported.
• Outlook rules – some of the actions known from the classic 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.
• The rendering engine – since the new Outlook is based on the web version (OWA), there is a huge change to how emails are composed and rendered. To put it simply, Outlook breaks its close connection to MS Word, which means it probably won’t add as much hidden formatting to emails and will allow more freedom when creating HTML email signatures and email templates.

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. Fun fact: You can schedule email delivery in classic Outlook as well, but it works a bit differently. See how
• 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.
• 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. Personally, I’m fine with classic themes, as long as the dark mode is supported.
• Folder colors, which is another way that may help you with organizing your Outlook. The classic Outlook let you color-code mailbox items, but not folders.

That’s not all, though – for a regularly updated list of the most recently added features that are especially interesting (and a few that are yet to come), jump to this section.

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

As I mentioned before, the new Outlook is already the default version for SMBs, while the Try the new Outlook button encourages classic Outlook users in Enterprise environments to check out the new experience. Regardless of your environment, 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. I’ll list some of the recently added features and some of the more interesting features yet to come:

Recently added

• New usage report for the new and classic Outlook for Windows – the report lets you check how many people are using each Outlook version in your organization. It was added to the Microsoft 365 admin center in early 2025, with a corresponding version in the Exchange admin center released soon after.
• Custom sounds for new email notifications – from summer 2025, you can add custom sounds to notify you when a new email arrives. This also works for mail reactions and Calendar notifications.
• Drag and drop to send emails and files between accounts – the ability to move emails and files between personal and enterprise accounts made its way to the new Outlook in September 2025. To enable this feature, the ItemsToOtherAccountsEnabled parameter must be set to true in the OWAMailboxPolicy.
• Warning about spoofing attempts – Microsoft now warns users of the new Outlook when they receive emails from unverified senders.
• Adding attachments while drafting an email offline – this feature was supposed to reach general availability in fall 2025, but it seems it’s still being rolled out. At this point, I half expect the rollout is happening offline, too.
• Offline support for creating, editing, and deleting calendar events – this offline functionality has actually been launched, to give credit where it’s due.
• Access to iCloud Mail, Calendar, and Contacts via Apple Account – there’s no longer a need to generate an app-specific password to access your iCloud data in the new Outlook. You can now simply enter your Apple Account in Outlook’s account setup wizard and sign in via the Apple website in your browser (thanks to OAuth 2.0).
• Wait on Send for oversharing – with this feature, admins can prevent an email from being sent if the DLP policy evaluation has not been completed for labeled or otherwise sensitive content.
• New app icon – this one clearly aims to keep our graphic designers busy updating icons in this article for the umpteenth time.
• Copilot support – rolled out to a growing number of users, Copilot can now summarize emails and linked attachments.
• Email templates – this useful option, available in the classic Outlook before, was reintroduced in the new Outlook in November 2025.
• Label-invoked add-ins – a change to a sensitivity label can now be defined as an event that triggers the activation of an Outlook add-in.
• Revamped signature settings – the Signatures settings page now provides more formatting options, similar to those available across other Office apps.

Planned for the future

• Teammates’ calendars in the left navigation pane – starting from March 2026, you’ll be able to see what your colleagues are up to using a preview in the left navigation pane.
• Inserting signatures into calendar events – rollout first planned for December 2024 was postponed to December 2025… and then again to April 2026.
• Import of PST files to a mailbox – as mentioned earlier, PSTs are staging a quiet comeback to the new Outlook. This feature is scheduled for spring 2026.
• Mail delegate permissions granted from the new Outlook – Microsoft is currently developing a feature to allow granting delegate access for mailboxes and folders from Outlook. Rollout start is scheduled for July 2026.

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 the new Outlook, the “missing features” section is the recurrent theme.

And now for the troubleshooting section. If you run into any issue I didn’t cover below, make sure to let me know in a comment.

Troubleshooting

New Outlook vs classic Outlook – which one is which?

After enabling the Try the new Outlook toggle, a new Outlook instance is created. You can launch either version from the Start menu. Now, distinguishing between them might be a slight problem, since both the classic and the new Outlook icons have evolved over time.

Initially, both Outlook versions had the same name, and the only quick way to tell them apart was to look at the icon: the new Outlook had the PRE label over it:

Later, the new Outlook icon got an upgrade – the PRE label was replaced with NEW, and the design was also changed. The (new) label was also added to the new Outlook’s name:

And now, when the new Outlook is officially out of the preview stage, its name and icon don’t have any annotations – it’s simply Outlook. Instead, as Microsoft announced, the classic Outlook gets the classic label starting with version 2407:

The truth is, these icons vary from environment to environment. So, at the moment, your classic Outlook icon might be different than my classic Outlook icon.

To avoid any doubts, you can create a shortcut to the right Outlook version or pin it to the task bar.

The default location of the classic Outlook is:

"C:\Program Files\Microsoft Office\root\Office16\OUTLOOK.EXE"

The default location of the new Outlook for Windows is:

“C:\Program Files\WindowsApps\Microsoft.OutlookForWindows_(version number)\olk.exe

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 anymore. 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.