Is It Safe to Delete OST File & What Happens If I Delete?

Mark Regan
Published: July 16th, 2024 • 7 Min Read

Have you ever wondered if is it safe to delete OST file that are taking up space on your computer? Many of us commonly face Outlook storage issues and look for quick solutions, but the idea of deleting an OST file seems risky. After all, it plays an important role in MS Outlook. So what exactly does this file do, what happens if I delete OST file or can I delete OST files without losing email messages? Today we will answer all these questions. Keep reading the article to know the role of an OST file, its importance, and whether deleting it is safe or not.

Is It Safe to Delete OST File?

Before we get to know whether is it OK to delete Outlook OST file or not, we should first understand the role of an OST file in Microsoft Outlook and what happens if you delete it.

OST file stands for Offline Storage Table which is used by Microsoft Outlook to store a copy or our emails, contacts, calendar events, and another mailbox on a computer. This file allows us to access our important emails and work with them even when we are not connected to the internet. Meanwhile, when you go back online, the changes you made will sync with the mail server. Most essentially, an OST file helps us to work offline and ensure that our data is always up-to-date.

Importance to Delete Outlook OST Files Safely:

Deleting an OST file safely is important to avoid data loss and ensure proper functionality. Remember that this is an Outlook data file (OST file) that stores a copy of your emails and all other data. So before you delete it, you should ensure that your Outlook OST data file is backed up or synchronized with the server to prevent any data loss problems. Keep reading the article to find out is it safe to delete OST file in Outlook.

What Happens If I Delete Outlook OST File?

Follow points will inform what happens if you delete Outlook OST file and delete OST files without losing email messages:

Slow Performance: Outlook may experience issues in downloading and synchronizing profile data from the server which can take longer time than usual.

Risk of Data Loss: After making changes in OST file offline and if they have not synced with server, then they may get lost.

Profile Corruption: In some cases, the Outlook profile also gets corrupt when the user does not delete OST file safely. If this happens after deleting OST file, then the user may need to recreate or repair the corrupt OST file.

Potential Errors: If you do not delete OST files safely or correctly then you can encounter several errors. Also issues with Outlook which you would require to troubleshoot and reconfigure.

Rebuilding the File: Outlook will recreate a new OST file once you open the application and connect to the mail server after deleting OST file.

Limited Offline Access: Users may experience limited access to their emails and other data in offline mode until the new OST file is fully recreated.

Loss of Configuration: Another thing that would happen after deleting the OST file is, you will lose all your custom settings like view, filters, etc, and cache data in the old OST file and may require re-configuration.

Data Recovery: The data like email, contacts, and calendar events stored on the server will be downloaded again into a new OST file.

Issues with Add-Ins: You will also need to reconfigure certain add-ins in Outlook can also after deleting OST file.

Delay in Search Indexing: After deleting an OST file, you may need to rebuild the search index which can take a lot of time and affect the search functionality.

Network Load: One more thing that can happen after deleting the OST file is, that the initial sync can create a heavy load on the network, especially for large mailboxes.

So Can I Delete OST Files Without Losing Email Messages?

If your query is, Is it safe to Delete OST file? Then the answer is Yes! To ensure a proper and secure deletion of OST files you should use BitRecover OST Converter Tool to create a backup of all the import files and delete OST files without losing email messages. This tool is perfect to ensure that you may not lose even a single piece of information from your OST file and keep it safely on your computer or anywhere you want.

After using this to create a backup, convert OST files to PST, MBOX, EML, MSG, TEXT, etc, or migrate OST to Office 365, Exchange server, Thunderbird, etc, you can peacefully delete all your OST files without worrying about losing messages and make sure it is safe to delete OST file.

How Do I Safely Delete OST File?

Finally, after using the tool, you can use the following steps to delete OST files without losing email messages.

  1. First of all, close the Outlook application if it’s open.
  2. Press Win+R using your keyboard to run the search box.
  3. Enter the command shown below in the box and click OK.
  4. After that, the OST file location will open on your computer.
  5. Select the OST file you want to delete and press the Delete button.
  6. Just after picking the Delete button, a confirmation message will appear on the screen:
    Are you sure you want to move this file to the Recycle Bin?
  7. Press the YES button to confirm.

However, it is relevant to think about whether is it safe to delete OST file or not, as, after the above steps, you need to recreate a new file to ensure a smooth running of Outlook. Follow steps mentioned below and create a new file on different path then synchronize it with Exchange server. Once the synchronization is complete, configure your Outlook account and start working with your new OST file.

Recreate to Ensure Is It Safe to Delete OST File

  1. Remember to close the Outlook app.
  2. Rename the existing OST file.
  3. Open Outlook and look for the following error message:
    The file “C:\Exchange directory\file name.OST could not be found
  4. Hit the OK button to safely delete OST files.
  5. Now go to Offline Folder File Settings and Click OK button.
  6. Hit Yes for the following Pop-up message:
    The file c:\Exchange directory\file name.OST' could not be found. Would you like to create it?
  7. Now go to the Tools Menu and select the Synchronize-All folders option.

So this is how to synchronize new OST files with Exchange server and ensure whether is it safe to delete OST file or not.

Also Read: How to Migrate OST to Exchange Server?


In short, we resolved query for users who were worried about is it safe to delete OST file or not. Therefore, safely deleting an OST file can make space and resolve various Outlook issues. However, it is important to carefully delete OST files to avoid data loss and functionality issues. Always remember to back up the data you are about to delete using trusted software.

BitRecover’s tool helps to safely delete OST files without losing email messages and store them securely wherever the user wants. Moreover, also describes the roles & importance of an OST file and what happens if I delete Outlook OST file. We hope the article helped and resolved the query is it safe to delete OST file or not!