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What is Ost Integrity Check?

Author

John Castro

Published Feb 17, 2026

What is Ost Integrity Check?

OST Integrity Check tool is an inbuilt utility provided by Microsoft to diagnose and repair synchronization issues. The OST Integrity Check tool (Scanost.exe) is installed automatically when you install Outlook. It performs some basic scanning and restores OST file structures where possible.

Keeping this in view, how do I run an OST Integrity Check?

You can check the location of your Outlook Data Files in Outlook.

  1. Select File > Account Settings > Account Settings.
  2. Select the Data Files tab.
  3. All Outlook Data Files (. pst) and Offline Data Files (. ost) are listed along with the name of the account the files are associated with.

Secondly, what is an OST file? Offline Outlook Data File (. ost) Most other account types, such as IMAP accounts, Microsoft 365 accounts, Exchange accounts, and Outlook.com accounts use an Offline Outlook Data File (. ost) file to store a synchronized copy of your mailbox information on your local computer.

Besides, how do I know if my OST file is corrupted?

Step 2: Methods Available for Repairing OST file

  1. Open >> Control Panel >> Select Mail option >> Tap on Show Profile.
  2. Choose the profile name and click on properties.
  3. Click on Email Accounts.
  4. In Account Settings, select Data files >> File Path.
  5. Select Open File Location.
  6. Delete the corrupted OST File.

What is a corrupted OST file?

The OST file is a synchronized copy (cached Outlook items) of the account saved on your machine. Here's the default location of the OST file: drive:\Users\\AppData\Local\Microsoft\Outlook. Corruption is a common problem with Outlook data files when any unfavorable circumstances happen inside them.

What is the difference between OST and PST?

OST is called Offline Storage Folder, while PST is called Personal or Online Storage Folder. OST files let the user read, reply, compose and view the mails even in the offline approach, whereas in the PST file format, you can't enjoy the advantage of such a feature. OST files just support the Microsoft exchange server.

How do I recover an OST file?

Here are the steps to recover:
  1. Open Exchange Email application (Outlook) in offline mode.
  2. Click on File menu > Open & Export > Import/Export.
  3. Import & Export wizard will appear, click on Export to a file > Outlook data file (.
  4. Choose the OST folders which contain the required Exchange information and click Next button.

How do I open an OST file for free?

OST Viewer
  1. Download, install, and run Recovery Toolbox for Outlook.
  2. Select OST file on the first page of Recovery Toolbox for Outlook.
  3. Choose a conversion mode (or restore if the OST file is damaged)
  4. Get access to folders, letters, contacts, and more on the preview page.

Can ScanPST scan OST files?

In order to repair Outlook OST file, many users asked this can ScanPST can scan OST file? So the answer is Yes! But before proceeding further first we have to learn about Inbox Repair Tool ( Scanpst.exe ) And also we will discuss the reasons why the users OST file get corrupted or damaged.

How do I scan an OST file in Outlook 365?

To begin the repair process, exit MS Outlook application. After that, run the scanost.exe file from the local machine. Then, look for the OST file that is to be repaired and click on Open option. Now, click on the Begin Scan option and the software start scanning file for errors.

Is not a Outlook data file Ost?

In simple terms, OST is a copy of your current mailbox. One of the major reasons for OST not being considered as an Outlook Data File is that it doesn't support running on other instances. OST is not portable which means you can't expect an OST generated on one system to run on another.

Why is OST file corrupted?

Hard disk crash is very common that can happen due to the two most common reasons: logical failure or physical failure. Whenever a hard disk crashes down, all the stored data become inaccessible or corrupted. Since the OST files are stored on a local system, they may become corrupted due to storage media failure.

How do I repair an OST file in Outlook 365?

Solutions to Repair Office 365 OST File
  1. Click on the File.
  2. Select Account Settings, and afterward select Account Settings again in the drop–down menu.
  3. In the Email tab, select the file you wish to fix and click on the Repair.
  4. Click on the Next button.
  5. Outlook will finish the setup for your file.

How do I sync Outlook OST file?

Manual synchronization
  1. In the Folder List pane, click the folder that you want to synchronize.
  2. On the Tools menu, point to Send/Receive, and then click This Folder (Microsoft Exchange Server) to synchronize one offline folder, or click Send/Receive All to synchronize all offline folders.

How do I open an OST file?

You can directly access OST file by using Kernel OST Viewer tool. It is absolutely free to use tool, to access OST file data in absence of MS Outlook. Visit to download the software to access OST emails easily.

How do I create an OST file in Outlook 365?

Create a new PST file and copy OST items
  1. Start the Outlook Application from the Application menu. Click Open.
  2. Click New Items, then go to More items present as the last option.
  3. After creating a new PST file, you can move the data to the new data file folder.
  4. Choose the new data file folder and then click OK button.

What happens if we delete .ost file?

Many users have a query that Is it safe to delete Outlook OST file? So, there will be no data loss when the users remove an OST file because it can be again downloaded from Exchange Server. But it is recommended to take a backup of Offline Storage File into PST file format before going to the deletion process.

Which is better OST or PST?

PST is used to store file locally whereas OST is an Offline storage used when no server connection is present. PST file may be used for an Exchange set-up though is not recommended but unlike OST files, which are compatible only for an Exchange Server, is compatible with other servers too.

Is it safe to delete OST file?

OST files grow abnormally huge in size and their chances of corruption also get higher. In fact, these enormous OST files can be counted as a database, due to their vast size. Such OST files are prone to corruption leaving no other option for the user but to “delete OST fileâ€.

Do I need an OST file?

Outlook Data Files (. ost) are used when you have an Exchange account and want to work offline or use the default Cached Exchange Mode. This type of data file is also used for accounts that you set up with the Outlook Connector for Outlook.com.

Can I convert OST to PST?

You can manually convert OST to PST only when you are using Outlook with the original Exchange account. But the software converts the OST into PST format even without the original Exchange profile and Exchange Server connectivity. Also, you can convert 25 items from each folder to PST for free.

What is the maximum size of OST file?

50 GB

Does OST file contain calendar?

In general, the following is stored in the ost-file: Your mailbox data (mail, calendar, contacts, tasks, notes and journal folders). Hidden items and other “overhead†as found in a pst-file.

Why is my OST file so large?

OST file contains entire mailbox data which has been gathering since your user account has been created. From then, none of the data has been deleted and OST files have become oversized creating an error “ OST file too largeâ€. The large sized OST file contains the components such as: Hidden items.

What is Outlook OST file used for?

Outlook Data Files (. ost) are used when you have an Exchange account and want to work offline or use or use the default Cached Exchange Mode. This type of data file is also used for accounts that you set up with the Outlook Connector for Outlook.com (formerly Hotmail).

How do I run a repair on Office 365?

Double-click Programs and Features. Click MicrosoftOffice 365, and then click Change. Select Quick Repair, and then click Repair. You may have to restart your computer after the repair process is complete.

How do I run a repair in outlook?

How Do I Repair Microsoft Outlook?
  1. Right-click on Windows icon and select Apps and Features from the pop-up.
  2. Select Microsoft Office and click on Modify.
  3. Choose Quick Repair and click on Repair button to start the repair process.
  4. Restart the computer after the repair process and the application will be ready to use.

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