New Outlook vs Classic Outlook: Differences, and How to Switch Back When the Toggle Is Missing
Windows can now have two separate Outlook apps on it, and they do not do the same things. Here is how to tell which one you are in, what really differs, how to get back to classic Outlook when the toggle has gone, and what Microsoft has published about classic Outlook’s future.
In short: classic Outlook and the new Outlook are two separate apps. If you see a Settings gear at the top right, you are in the new Outlook; if not, classic. The new Outlook has no COM add-ins and no AutoArchive, and only partial support for PST files, offline use, rules, Quick Steps and Search Folders. To go back, use the toggle at the top right or Help > Go to classic Outlook. If the toggle is missing, open Outlook (classic) from the Start menu, install it if it isn’t there, or ask IT on a work account. Microsoft has published no end date for classic Outlook: it says existing installations are supported until at least 2029.
How to Tell Which Outlook You Have
Microsoft’s What version of Outlook do I have? page gives a one-look check for Windows:
- New Outlook: there is a Settings gear at the top right.
- Classic Outlook: there is no Settings button, and there is a File tab.
The Start menu helps too. Where both are installed, Microsoft names them Outlook (classic) and Outlook (new). Some newer Microsoft pages call the new app just “Outlook for Windows”. It is the same app. This post covers these two Windows apps only.
New Outlook vs Classic Outlook: The Differences
Microsoft keeps a feature comparison, last updated September 23, 2026 when this was written, and says it does not list everything. “Partially available” means the feature exists but might not have all of what classic Outlook has.
| Feature | Classic Outlook | New Outlook |
|---|---|---|
| COM add-ins | Available | Not supported |
| Web add-ins | Available | Available |
| PST files | Available | Partially available; needs classic Outlook installed too |
| Offline mail and calendar | Available | Partially available |
| Shared mailboxes | Available | Available; delegate access partially available |
| Rules | Available | Partially available; no import or export |
| Quick Steps | Available | Partially available |
| Search Folders | Available | Partially available; predefined criteria only |
| AutoArchive | Available | Not available |
| Microsoft 365, Outlook.com, Gmail, Yahoo, IMAP, POP | Available | Available |
| iCloud | Partially available | Available |
| On-premises Exchange | Available | Partially available, through IMAP (see below) |
| Multiple mail profiles | Available | Upcoming |
What the Differences Mean in Practice
- COM add-ins. Microsoft’s advice to organizations is to move to web add-ins. If you depend on a COM add-in, ask its maker whether a web version exists. This list of Outlook add-ins says where each one works.
- PST files. In the new Outlook, add a .pst under Settings > Files > Outlook Data Files. Classic Outlook must also be installed, with the same 32-bit or 64-bit architecture. Microsoft’s pages disagree on importing: the import article says the new Outlook can import, while the export article says importing a mailbox or calendar is “currently not supported”. If your archive lives in PST files, test before you rely on it.
- Offline. On by default in the new Outlook, with 30 days of email saved unless you choose 7, 90 or 180 under Settings > General > Offline. Viewing shared folders and using add-ins do not work offline.
- Shared mailboxes. Both apps open them. In the new Outlook, right-click your account name and select Add shared folder or mailbox, or go to Settings > Accounts > Shared with me.
- Rules. New Outlook: Settings > Mail > Rules. Classic Outlook: File > Manage Rules & Alerts. Some classic rules can’t be processed by the new Outlook because they are client-side, so you recreate them (see client-only vs server-side rules). Microsoft also says the new Outlook does not support rules for Gmail, Yahoo and iCloud accounts.
- Quick Steps. On the Home tab in both. In the new Outlook, the Quick steps drop-down has Manage quick steps. Microsoft marks them partially available without saying which parts are missing, so check the ones you use.
- Search Folders. In the new Outlook they use predefined criteria. Advanced custom Search Folders are classic Outlook only.
- AutoArchive. Microsoft says it is not available in new Outlook, although the comparison table leaves it out. In classic Outlook it is under File > Options > Advanced > AutoArchive Settings. Online archive is a separate feature and is available in both. For other ways to clear old mail, see how to move old emails automatically.
- On-premises Exchange. Microsoft’s pages disagree again. The comparison says partially available through IMAP; the supported accounts page says these accounts aren’t supported. Check with IT before switching.
Why the Toggle Appears
The toggle is how Microsoft moves people between the two apps. Classic Outlook shows Try the new Outlook at the top right. Turning it on downloads the new app, closes classic Outlook and opens the new one, where you can import your accounts and settings. The new Outlook shows a New Outlook toggle for going back.
You may also have been moved without touching it. Microsoft lists these automatic switches, each after in-app notices:
- Personal accounts, from October 2024, when all your accounts in classic Outlook and your Office sign-in are personal Microsoft accounts, and the license is a personal subscription. The same page says both that Gmail and Yahoo accounts are included and that they won’t be switched.
- Business plans, from January 2025, on the Current Channel.
- Enterprise plans: not switched “at this time” (dates below).
To stop an automatic switch, in classic Outlook go to File > Options > General > New Outlook options and clear Automatically switch me to new Outlook. If that option isn’t there, Microsoft says you aren’t currently eligible for the switch.
How to Switch Back to Classic Outlook
- In the new Outlook, select the toggle at the top right.
- Choose Switch back to classic Outlook. Classic Outlook opens from then on.
- Or choose Use classic Outlook this time. It opens classic Outlook now, and later launches still go to the new Outlook.
Help > Go to classic Outlook on the ribbon also opens it.
Switch Back to Classic Outlook: Toggle Missing
Microsoft says the toggle may not appear if classic Outlook isn’t installed, and that an admin can hide it. Try these in order:
- Use the Help tab. In the new Outlook, select Help > Go to classic Outlook.
- Use the Start menu. Open Outlook (classic) directly, choosing the icon without a “New” tag.
- Install classic Outlook if it isn’t there. New Windows PCs may not have it, or the icon may fail with an error that the app isn’t available in the Microsoft Store. On Microsoft’s Install or reinstall classic Outlook page, pick your language, select Download and follow the prompts. That page does not say which licenses it needs. If it fails on a work or school account, it tells you to contact IT.
- If the toggle is still missing, or classic Outlook keeps opening the new one, Microsoft’s fix is in the registry. Open Registry Editor, go to
HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Preferences, double-click UseNewOutlook and set the value to 0. Then open classic Outlook from the Start menu again. On a work PC, ask IT first. - Ask IT on a work or school account. Admins have a policy that hides the toggle so that people stay in the new Outlook. If you don’t see it, ask IT.
If it is Try the new Outlook that is missing from classic Outlook, Microsoft gives several reasons: an admin hid it, the account isn’t supported (some work or school accounts aren’t), or the account is tied to a one-time Office purchase or a standalone Outlook. You can still open the new Outlook directly, without the toggle.
Microsoft’s Timeline for Classic Outlook
Microsoft describes three stages: opt-in (new Outlook off by default), opt-out (on by default, and you can go back) and cutover (you can’t go back, and new Microsoft 365 deployments get the new Outlook).
| When | What Microsoft says |
|---|---|
| August 2024 | New Outlook generally available |
| October 2024 | Automatic switching starts for qualifying personal accounts |
| January 2025 | Automatic switching starts for Business plans on the Current Channel |
| March 2027 (per message center) | Opt-out stage begins for Enterprise, moved from April 2026 |
| No date published | Cutover, with at least 12 months’ notice to admins |
| Until at least 2029 | Existing classic Outlook installations stay supported |
March 2027 comes from message center post MC949965, updated in February 2026. Those posts are visible to admins, so the link here is a third-party copy. It says people on a perpetual license or an on-premises account won’t be migrated. The stages page, last changed in February 2026, gives neither that date nor a cutover date. The date has moved once already, so check again before planning around it.
“At least 2029” is a minimum. One-time purchases have their own dates: Microsoft lists Office 2021 as retired in October 2026 and Office 2024 in October 2029.
Which One Should You Use?
Stay in classic Outlook if you rely on a COM add-in, AutoArchive, client-side rules, custom Search Folders or PST files. Microsoft also recommends keeping both installed for organizations that need full PST support or Mail merge in Word. Otherwise, try the new Outlook and keep classic beside it: Microsoft says it will maintain the ability to run both side by side.
If you file mail into folders by hand, Folder Suggest, an add-in that suggests a folder for each email, runs in both and has a free plan.
Frequently Asked Questions
What is the difference between new Outlook and classic Outlook?
They are two separate Windows apps. Classic Outlook has COM add-ins, AutoArchive and custom Search Folders; new Outlook does not, and some classic client-side rules don’t carry over. Microsoft also lists PST files, offline use, rules, Quick Steps and Search Folders as only partially available in new Outlook. Web add-ins and shared mailboxes work in both.
How do I know if I have new Outlook or classic Outlook?
Look at the top right of the window. A Settings gear means new Outlook. No Settings button means classic Outlook, which also has a File tab. In the Start menu the two can appear as Outlook (classic) and Outlook (new).
How do I switch back to classic Outlook?
In new Outlook, select the toggle at the top right, then Switch back to classic Outlook. To open classic Outlook once without switching, choose Use classic Outlook this time. Help > Go to classic Outlook on the ribbon also works.
How do I switch back to classic Outlook if the toggle is missing?
Try Help > Go to classic Outlook, or open Outlook (classic) from the Start menu. If it is not there, install it from Microsoft’s Install or reinstall classic Outlook page. If it keeps opening new Outlook, Microsoft’s fix is to set the UseNewOutlook registry value to 0. On a work or school account your admin may have hidden the toggle, so contact IT.
Why did Outlook switch me to new Outlook?
Microsoft switches qualifying personal accounts (since October 2024) and Business plans on Current Channel (since January 2025) after in-app notices. To stop it, go to File > Options > General > New Outlook options in classic Outlook and clear Automatically switch me to new Outlook. Enterprise plans are not switched automatically at this time.
When will classic Outlook end?
Microsoft has published no end date. It says existing installations will be supported until at least 2029. Microsoft’s message center says the Enterprise opt-out stage, with new Outlook on by default and a way back, begins in March 2027 for people not exempted by policy or license. Its public stages page doesn’t give that date, and it has moved once. The stage with no way back has no published date.