Have you recently noticed that Classic Outlook has mysteriously disappeared from your Microsoft 365 installation? You’re not alone. I recently encountered this issue with multiple clients and discovered that Microsoft has started replacing the Classic Outlook application with the new Outlook for Windows app, often without any notification or consent from users. This can be particularly problematic for business users who rely on specific features only available in Classic Outlook, such as POP3 with PST files.
In this guide, I’ll walk you through exactly how to restore Classic Outlook when it disappears and explain the key differences between the Classic and new versions that might impact your workflow.
Key Takeaways
- Microsoft is gradually replacing Classic Outlook with the new Outlook for Windows app in Microsoft 365 installations
- The Classic Outlook version can be restored by downloading it from the Microsoft Store (even though it doesn’t appear in search results)
- Classic Outlook supports important business features like POP3 with PST files that may not be fully implemented in the new Outlook app
Requirements
- A computer with Microsoft 365 installed
- Internet access to download Classic Outlook from the Microsoft Store
- Valid Microsoft 365 license that includes Outlook
Why Does Classic Outlook Disappear from Microsoft 365?
Microsoft has been gradually transitioning users from the Classic Outlook application to the new Outlook for Windows app. The new version is free but contains ads and, at the time of writing, lacks some important functionality that business users rely on. This transition happens in two scenarios I’ve encountered:
- During fresh installations of Microsoft 365
- Through updates to existing Microsoft 365 installations
This change can be particularly disruptive for users who depend on features exclusive to Classic Outlook, such as POP3 mail setups with PST files containing years of important email data.
Understanding Email Setup Differences in Outlook
Before explaining the solution, it’s important to understand the differences between email setup types in Outlook, as this highlights why many users still prefer the Classic version.
POP3 vs. IMAP: Key Differences
POP3 and IMAP are two different protocols for retrieving emails, and they work quite differently in practice:
- POP3 Setup (Available in Classic Outlook)
- Emails are saved to a PST file on your computerCreates true offline copies of every emailYou retain access to emails even if they’re deleted from the serverYou can choose when to delete emails from the server
- IMAP Setup
- Emails are synchronized with an OST fileOnly recent emails are truly available offlineWorks as a mirror between your client and the serverIf emails are deleted from the server, they’ll be deleted from Outlook too
While IMAP is the modern standard, many business users still prefer POP3 for its reliability with offline access and the security of having a true local copy of all emails.
PS. You can get the full Outlook infographic for free on Gumroad, if you’re interested.
How to Restore Classic Outlook When It Disappears
After encountering this issue multiple times, I found a reliable solution to restore the Classic Outlook application:
Download Classic Outlook from Microsoft Store
- Visit the Microsoft Store download link for Classic Outlook.
- Download and install the application (Note: This isn’t easily found through a normal search in the Microsoft Store).
- Once installed, open Classic Outlook – your existing mail profile should automatically load.
- Verify that all your email accounts and past emails are accessible.
- Consider uninstalling the new Outlook for Windows app to prevent confusion.
Optional: Prevent Future Automatic Replacement
You can add registry keys to prevent Microsoft from automatically replacing Classic Outlook in the future:
Important Note: Always back up your registry before making changes. Incorrect registry modifications can cause system issues.
Users on this Reddit Post has suggested adding the following entries:
reg.exe add "HKCU\SOFTWARE\Policies\Microsoft\Office\16.0\Outlook\Preferences" /v NewOutlookMigrationUserSetting /t REG_DWORD /d 0 /f
reg.exe add "HKCU\SOFTWARE\Microsoft\Office\16.0\Outlook\Preferences" /v UseNewOutlook /t REG_DWORD /d 0 /f
reg.exe add "HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\Options\General" /v DoNewOutlookAutoMigration /t REG_DWORD /d 0 /f
To add an entry, simply launch Windows Powershell, Terminal or Command Prompt as Admin and run the commands one by one.
Why Classic Outlook Matters for Many Users
The Classic version of Outlook is a premium application that’s part of the paid Microsoft 365 suite. There are several reasons why users might prefer it over the new version:
- Full support for POP3 with PST files
- No advertisements
- More comprehensive business features
- Better offline capabilities
- Familiar interface for long-time users
While Microsoft is pushing users toward the new Outlook for Windows app, many businesses and power users still depend on Classic Outlook’s unique features.
Conclusion
Microsoft’s decision to replace Classic Outlook with the new Outlook for Windows app without clear notification has created challenges for many users, especially those who rely on POP3 with PST files. Fortunately, the solution is relatively straightforward – downloading Classic Outlook from the Microsoft Store. This allows you to continue using the premium version you’ve paid for with all its advanced features.
If you’re experiencing this issue, try the steps outlined above to restore your Classic Outlook. The process is quick and should immediately give you access to all your previous email accounts and data.
Frequently Asked Questions (FAQ)
Why is Microsoft replacing Classic Outlook with the new Outlook app?
Microsoft is moving toward a unified email experience across platforms and introducing new cloud-based features. However, this transition has been controversial because the new app currently lacks some important functionality from Classic Outlook.
Will my PST files work with the new Outlook for Windows app?
At the time of writing, the new Outlook for Windows app does not support PST files, though Microsoft has indicated this feature may be added in the future. For now, users who need PST file access should use Classic Outlook.
Do I need a Microsoft 365 subscription to use Classic Outlook from the Microsoft Store?
Yes, even when downloaded from the Microsoft Store, Classic Outlook still requires a valid Microsoft 365 license to function. It’s not available as a standalone purchase.
What’s the difference between OST and PST files in Outlook?
PST files (used with POP3) create true offline copies of emails stored locally on your computer. OST files (used with IMAP) are synchronization files that mirror what’s on the server but don’t necessarily maintain complete offline copies of older emails.
Can I have both Classic Outlook and the new Outlook app installed simultaneously?
Yes, you can have both installed on the same computer. However, this might cause confusion as they’ll appear similar in your Start menu. I recommend using only one version to avoid potential conflicts with your email profiles.
