How to Open OST File in Outlook

This article provides a detailed guide on how to open OST files in Outlook. It explains the problem, causes, and offers three solutions along with recommendations for software tools. Additionally, it answers frequently asked questions related to the topic, clarifies technical terms, and provides helpful tips.

Nene Aly

By Nene Aly / Updated on March 4, 2024

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Problem: Unable to Open OST File in Outlook

If you're unable to open an OST file in Outlook, you might be facing a common issue that many users encounter. The problem arises when Outlook fails to synchronize the OST file with the Exchange server, preventing you from accessing your emails, contacts, and other data.

Main Causes of the Problem

There are several reasons why you may encounter difficulties opening an OST file in Outlook:

  1. Corrupted OST file
  2. Incompatible Outlook version
  3. ISSUE 3

Solution 1: Repair Corrupted OST File

If the OST file is corrupted, you can try repairing it using the built-in Inbox Repair Tool (Scanpst.exe). Follow these steps:

  1. Close Outlook if it's open.
  2. Open the Scanpst.exe tool by searching for it in the Windows search bar.
  3. Click the 'Browse' button and locate the OST file you want to repair.
  4. Click 'Start' to initiate the scanning and repair process.
  5. Once the repair is complete, open Outlook and check if you can now access the OST file.

Solution 2: Convert OST to PST

If the OST file is still not opening, you can convert it to a PST file format that Outlook can easily read. Follow these steps using the OST to PST conversion tool:

  1. Download and install the OST to PST conversion tool on your computer.
  2. Launch the software and click the 'Add File' button to import the OST file.
  3. Select the desired conversion options, such as file format and file location.
  4. Click 'Convert' to start the conversion process. This may take some time depending on the size of the OST file.
  5. Once the conversion is complete, open Outlook and import the converted PST file.

Solution 3: Use Third-Party OST Viewer

If you don't want to convert the OST file to PST but still need to access its contents, you can use a third-party OST viewer tool. These tools allow you to open and view the OST file without the need for Outlook. One recommended tool is 'OST Viewer Pro'.

OST Viewer Pro is a feature-rich software that offers a user-friendly interface, advanced search options, and the ability to export data in various formats. However, keep in mind that the free version has limited functionality and the pro version requires a purchase.

FAQs (Frequently Asked Questions)

Q: Can I convert an OST file to a PST file without Outlook?

A: Yes, using third-party conversion tools like 'OST to PST Converter' allows you to convert OST files to PST format even if you don't have Outlook installed.

Q: How can I recover deleted items from an OST file in Outlook?

A: Unfortunately, once an item is permanently deleted from an OST file, it cannot be easily recovered. It's recommended to regularly back up your data to prevent such losses.

Q: Can I access an OST file on multiple devices?

A: No, OST files are primarily linked to the device and Outlook profile they are created on. They cannot be accessed or synchronized across different devices like emails stored on an Exchange server.

Q: Is it possible to merge multiple OST files into one?

A: Yes, you can use the OST to PST conversion tool to convert multiple OST files to PST and then import them into a single Outlook profile.

Q: Does Outlook automatically sync the OST file with the Exchange server?

A: Yes, Outlook typically syncs the OST file with the Exchange server whenever there is an active internet connection. However, if synchronization issues occur, you may need to troubleshoot or repair the OST file.

Q: Can I compress an OST file to reduce its size?

A: No, OST files are already compact and optimized for offline usage. Compressing them won't result in significant size reduction.

Q: How can I prevent OST file corruption?

A: Regularly backing up your OST file, using reliable antivirus software to prevent malware, and avoiding sudden computer shutdowns can help prevent OST file corruption.

Explanation of Technical Terms

OST: Stands for 'Offline Storage Table,' which is an offline copy of the mailbox items that enable you to work with Outlook even when you don't have an internet connection.

Scanpst.exe: Also known as the 'Inbox Repair Tool,' it's a built-in utility provided by Microsoft to repair corrupted PST and OST files.

OST Viewer Pro: A third-party software that allows you to open and view OST files without the need for Outlook. It offers advanced features for searching and exporting data.


  • Regularly backup your OST files to prevent data loss.
  • Keep your Outlook updated to ensure compatibility with OST files.
  • Use OST to PST conversion tools as a last resort if other methods fail.


In this article, we have explored various solutions to open OST files in Outlook. Depending on the cause, you can repair the OST file, convert it to a PST format, or use a third-party OST viewer tool. Additionally, we provided recommendations for the 'OST Viewer Pro' software and answered frequently asked questions related to opening OST files in Outlook.

Nene Aly
Nene Aly · Editor