XST File Extension
Microsoft Outlook Personal Folders Format
- File Type xst
- Developer Microsoft
- Popularity
- Application Microsoft Outlook
- Category Settings Files, Data Files
- Format XML
What is a XST file?
Microsoft Outlook Personal Folders Format works with the XST file extension and is classified under Settings Files and Data Files, with a total of 7386 files.
With the creation of the Microsoft Outlook Personal Folders Format (XST), Microsoft introduced file format along with 242 programs built for their use.
XST files are supported by Mac OS, Windows and Linux. You can create a XST file using one of 4 programs, for example Microsoft Outlook, Microsoft 365 and Microsoft Exchange Server.
Programs that support XST files
How to open a XST file?
The most common reason why a XST file cannot be opened is the absence of required software. To fix this, select a compatible program from the list. Then visit the official developer website via the provided link, download the program, and install it on your system.
The most popular programs for working with XST files are Microsoft Outlook, Microsoft 365 and Microsoft Exchange Server. To get the latest version of Microsoft Outlook, open the Microsoft website where a universal installer for all operating systems is available.
Once setup is done, your operating system should assign Microsoft Outlook as the default app for XST files.
Make Microsoft Outlook the default XST viewer
Changing the default program in Windows
- Start by right-clicking on your XST file and selecting the "Open With" option. From there, click "Choose another app" to continue;
- Inside the popup window, scroll through the list of applications and specifically choose Microsoft Outlook as the application to associate with your XST file;
- Check the "Always use this app" checkbox and click "OK".
Change the default app to open files on Mac
- Right click or use Control + Left Click on the desired XST file to access a dropdown menu of actions;
- Select "Open in application" and click "Other";
- Scroll down to the bottom of the window, where you will find the "Enable" menu. Default, "Recommended Programs" will be selected;
- In this menu, choose "All Programs" and navigate to Microsoft Outlook. Check the box next to "Always open in app" to make it the default program.
How to edit a XST file?
To edit XST files, you need to install specialized software that allows you not only to open but also to modify settings files. Online XST editors usually provide fewer features than software created specifically for Microsoft Outlook Personal Folders Format.
List of Top XST editors 2026
Following these criteria, we have put together a list of recommended XST editors.
| XST Editor Software | Developer | Platforms | Overall Rating |
|---|---|---|---|
| Microsoft Outlook | Microsoft | Windows, Mac OS | 4.8 out of 5 (43 reviews) |
Finding answers to XST file problems
If you encounter issues with XST files, don’t worry—most can be fixed with minor software adjustments. Refer to the troubleshooting tips below.
What are the signs that my XST file is damaged?
Corrupted XST settings files may have one or more of the following symptoms:
- Poor performance when editing a file in Microsoft Outlook;
- Opening or processing the file in Microsoft Outlook or other programs causes instability or crashes in the program;
- The file shows errors when trying to open it or does not open completely;
- Unexpected expansion of the total size of the XST file;
- Working with the file triggers the display of error messages;
Why does Microsoft Outlook quit or crash unexpectedly?
Microsoft Outlook crashes can be attributed to outdated software. Make sure you have installed the latest updates for Microsoft products.
A computer restart is often the key to solving numerous common problems. That’s why, it is recommended to restart the computer before making any changes to the software settings.
What methods can be used to repair a damaged XST file?
Use a recovery program to open the damaged XST file and navigate to the "Repair" menu item. Wait for the recovery process to finish, as it will automatically repair damaged settings files.