OST File Corruption Reasons and Their Solutions

Updated On - December 1, 2022 by Henry Bray |

Reading Time: 4 minutes

We already know that Outlook is the most popular email client and is used by a large number of users across the globe. Microsoft Outlook uses an Offline folder (OST file) to allow its users to work offline without any issues. The Outlook IMAP accounts such as and Outlook 365 account store their mailbox data in OST file format. But, What if the file gets damaged due to any reason and all stored data becomes incomprehensible?

Therefore, in this article, we will discuss the common causes of OST file corruption and the best possible ways to recover an OST file and a trick from solving this corruption issue. So lets we start the discussion.

Brief About OST File

OST files are a user mailbox content replica stored on the Exchange server. It is automatically created on the first use of Microsoft Outlook as soon as you connect to the server. Once created, the data is synchronized with the e-mail server so that it can be used offline and in the event of a shutdown of the e-mail server. The user can create email and other data elements in the OST file, even when you are not connected to the server. But, once you get the connection, the local file is synchronized with the server again, and these data items are automatically saved directly to the server.

Upon return of the connection, the OST file is automatically synchronized with the Exchange Server mailbox. It looks comfortable, but in reality, it is not. Like other programs and files, corruption occurs with OST files. Let’s examine the reasons.

What’s the Reason behind OST file corruption?

During the synchronized process, if your OST data is disrupted due to bad internet connectivity, the OST file may be damaged. Once the OST files are disabled, the Outlook functionality will also be affected. In addition to these reasons, there are many other causes of OST file corruption, clearly divided into two categories: hardware and software.

Hardware Related Issues

The corruption issues related to hardware are mainly caused due to inappropriate configuration, malfunctioning, failure in the external components of the computer system such as network connectors, hard drive, modem, internal or external power unit, etc

  • Delay due to network connectors
  • Affected storage device
  • Bad sectors on a hard drive
  • Sudden power loss/Surges

Software Reasons

If you have problems with logical inconsistencies, all of them are subject to software issues. These errors occur due to error transmission, viral infection, application failure, and downloading of programs from some unreliable source. Some errors are as follows:

  • Outlook program failure
  • Abnormal Extinction of Outlook
  • Add inappropriate Outlook
  • Specific storage limitation

Six Most Common Solutions to Fix OST file Problems

Method #1: Start Outlook in Safe Mode

The main reason behind starting the Outlook in Safe Mode is to disable the add-ins, which can cause errors in the boot process. This allows it to work safely without corrupting any add-ons or files. To open MS Outlook in safe mode, use this command – “outlook.exe / safe”.

Method #2:  Update the Folder

This method allows you to change the properties of folders and fix inaccessible OST file problems. This procedure applies to Outlook 2010.

  • First, right-click the folder and click Properties.
  • A dialogue box will appear. Click the “Clear Offline Items” option and hit the OK button.
  • Next, on the Outlook 2010 ribbon, click the Send / Receive option.
  • Finally, click the Update Folder to save the changes.

Method #3: Disable Firewall settings

You can render antivirus programs and other firewall settings inoperative as some programs are designed to scan and detect problems for all incoming and outgoing e-mails. If you turn on the antivirus option, it may disrupt the operation of MS Outlook on time. So you can try disabling the settings and rebooting Outlook to see the changes.

Method #4: By Compacting the OST file

Having an oversized OST file may create troubles and errors such as – tediousness in Outlook performance, OST file corruption, etc.; the data still exists in the deleted folder, even when you delete the data or any items. To delete items in your “Deleted Items folder”, you must individually remove all items that consume your lots of time. Therefore you can use the compact OST file option as it reduces the additional space acquired by these files.

Method #5: Use scanost.exe Tool

Microsoft gives users two integrated tools, such as ScanPST.exe or Inbox Repair Tool and ScanOST.exe or OST Integrity Checker, to repair small issues in Exchange OST files. The Scanost.exe tool scans all the mailbox elements that are included in the OST files and are presented on the Exchange server. This tool assures users to fix minor corruption issues related to the OST file.

OST File Corruption Reasons and Their Solutions

However, the OST integrity check is only available in Outlook 2007 and its previous versions, and it is discontinued in Outlook 2010 and later. You can use the Inbox Repair Tool to fix errors found in both OST & PST files created in that particular Outlook version.

Drawbacks of Scanost.exe tool

There are some limitations associated with the ScanOST.exe or OST integrity checker. Take a look at the points below:

  • It is not possible to recover lost emails or other items from the OST file.
  • Only minor corruption can be detected in the OST file.
  • Security is not provided when recovering data.
  • Do not repair Outlook 2010 and later versions.

Method #6: Make Use of Professional Software

If these manual methods don’t work, you can take the help of some professional tool. You can opt to Regain OST Recovery tool to fix the OST file corruption issues. This utility is useful because it corrects all types of corruption and restores data files.

Free Download100% Secure Buy NowPrice: $39

It can also transfer data from corrupt OST files to other file formats. The utility has the fastest scanning speed and is supported in all versions of Outlook. You can download the demo version of this tool for free.


I have described above the main causes and solutions of OST file corruption. When corruption in Outlook OST files is unexpected, you can try the above solutions. However, it is best to use an OST Repair tool as this will help you in repairing Outlook PST file and restore your data without any trouble. I hope this article helps you with your doubts.

Author: Henry Bray

Henry Bray is a young technologist and content a Content Writer at Regain Software, loves to write about MS Outlook, MS Exchange Server, Office 365, Mozilla Thunderbird and many more email applications.

One thought on “OST File Corruption Reasons and Their Solutions”

  1. Avatar Danielle says:

    I was starting to worry about OST file corruption, but now I’m glad to know that there are solutions out there. Great job on putting together all this information in one place!

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