The new Outlook for Windows app does not open or import PST files. This is a known limitation of the web-based architecture. You cannot directly access local PST data files within the new app interface.
This article explains why PST support was removed and the technical background. You will learn several methods to access your PST data and move your information to supported cloud accounts.
Key Takeaways: Accessing PST Data with the New Outlook
- Classic Outlook Desktop App: Use the traditional Outlook program to open PST files and export data to an online account.
- Import/Export Wizard: Transfer PST contents like emails and contacts to an Outlook.com or Microsoft 365 account.
- Outlook on the Web: Upload PST files to a OneDrive folder and use the web interface to import mail items.
Why the New Outlook App Cannot Use PST Files
The new Outlook app is built on the same code foundation as Outlook on the web. It is designed primarily to connect to cloud-based email services like Microsoft 365, Outlook.com, and Gmail. These services use online protocols such as Exchange ActiveSync and modern authentication.
PST files are a legacy local storage format from the classic Outlook desktop application. They are stored directly on your computer’s hard drive or a network location. The new app’s architecture does not include the components to read from or write to these local disk files. Microsoft’s direction is to move all data to the cloud for better security, sync, and accessibility across devices.
What Data is Stored in a PST File
A PST file acts as a local container for your Outlook information. It typically holds email messages from POP3 or IMAP accounts, calendar appointments, contact entries, tasks, and notes. When you use an Exchange or Microsoft 365 account in cached mode, a similar but different file type called an OST file is used for offline storage.
Steps to Migrate Data from a PST File
To use your PST data with the new Outlook app, you must import its contents into a cloud-based account. The classic Outlook desktop application is required for this process.
Method 1: Import PST Data to a Microsoft 365 or Outlook.com Account
- Open the classic Outlook app
Search for “Outlook (Desktop)” in the Windows Start menu. Ensure you are not opening the new Outlook app, which has a different icon. - Add your PST file to the classic app
Go to File > Open & Export > Open Outlook Data File. Navigate to and select your PST file. It will appear as a separate set of folders in your folder pane. - Use the Import/Export Wizard
Go to File > Open & Export > Import/Export. Choose “Export to a file” and click Next. Select “Outlook Data File (.pst)” and click Next again. - Select the target folder and account
In the wizard, select the top-level folder of the PST you just opened. Check the box for “Include subfolders.” Click Next. Choose the option to “Replace duplicates with items exported” and click Finish. - Choose the destination account
In the next window, you will be prompted to create a new PST file. Instead, click the “Browse” button and navigate to your primary mailbox folders under your Microsoft 365 or Outlook.com account name. Select the destination, such as your Inbox, and click OK to start the copy process.
Method 2: Upload PST to OneDrive for Outlook on the Web
- Upload your PST file to OneDrive
Open File Explorer and navigate to your PST file. Drag and drop the file into your OneDrive folder. Wait for the sync to complete. - Open Outlook on the web
In a browser, go to outlook.office.com and sign in with your Microsoft 365 or Outlook.com account. - Initiate the import
Click the gear icon for Settings. Go to View all Outlook settings > Mail > Accounts. Select “Upload email” under the “Upload email from a file” section. - Select the PST file
Click “Choose File” and navigate to your OneDrive. Select the uploaded PST file. Choose which folders to import and select a destination folder in your mailbox.
Common Issues When Moving Away from PST Files
Error: “Cannot open the Outlook window” when opening PST
This usually means the PST file is corrupted. Run the Inbox Repair tool on the file. Search for “SCANPST.EXE” on your computer, run it, and point it to your PST file to attempt a repair before importing.
The import process is very slow or gets stuck
Large PST files over 10 GB can cause performance issues. In the classic Outlook, try exporting data in smaller chunks. Export one major folder at a time, like the Inbox, instead of the entire PST file.
Need to keep a local archive for compliance
If you must retain a local copy, use the classic Outlook app in parallel. You can switch between the new and classic apps. Configure the classic app to use the PST file and keep it running on a specific machine for archive access only.
Data Storage Options: PST vs. Cloud Mailbox
| Item | Local PST File | Cloud Mailbox (Microsoft 365/Outlook.com) |
|---|---|---|
| Primary Access Method | Classic Outlook desktop app only | New Outlook app, Outlook on the web, mobile apps |
| Storage Location | Your computer’s hard drive | Microsoft cloud servers |
| Multi-Device Sync | Not available | Automatic across all signed-in devices |
| File Size Limit | 50 GB maximum in classic Outlook | 100 GB mailbox standard for many business plans |
| Backup Responsibility | Your responsibility | Handled by Microsoft with geo-redundancy |
| Search Functionality | Limited to local Windows Search index | Fast, server-side search across all mail |
You can now access your old PST data by importing it into a cloud account. Use the classic Outlook Import/Export Wizard for the most control over the transfer. For ongoing use, consider enabling the Archive mailbox feature in Microsoft 365 for online long-term storage instead of creating new PST files. A final tip is to use the new Outlook’s connected accounts feature to bring all your cloud email into one unified inbox.