Is It Safe To Delete OST File and What Happens If You Delete OST File?

Written By Ashwani Tiwari
Anuraag Singh
Approved By Anuraag Singh
Published On August 29th, 2023
Reading Time 6 Minutes Reading

Yes, you can deleted the OST file, but there are several details you should be aware of. Microsoft Exchange profile should be active and in good health. Data added in offline mode will be erased. Seems confusing, don’t worry, other details are explained in the below section.

In my organization, we use hosted Microsoft Exchange Server to centrally manage the emails. A few days back, I had access to my colleague’s Exchange account for some business work. Now the work has been done. So I would like to know, is it safe to delete OST file? Will anything bad happen if I eliminate the offline folder file?

Are you also facing the same problem? Are you worried about what will happen if we delete OST file? Then, all of your queries are resolved by this article. In the following section, we are going to discuss the Offline Storage File and the need to eliminate an old .ost file. Also, how to delete .ost files without losing email messages.

What is Outlook Offline Storage Table File (OST)?

  1. Whenever a user adds an account to Outlook, automatically a local copy of the data is saved on the system. This will allow the users to access already stored email messages, calendars, and much more without an internet connection.
  2. Most of the account types, such as Office 365, Exchange accounts, and use an Offline Outlook Data File (or .ost) file. This file stores all the modified Outlook information performed in the absence of an internet connection. So, whenever users’ account connects to the internet, changes made in the Microsoft Outlook account get synchronized with the mail server.
  3. The email messages will not be sent and no new mail will be downloaded until your internet connection is restored. But, the users can view previous data and compose the new messages that will be saved in the OST file.

Now, we know what are OST files. We will now describe the reasons for deletion and is it safe to delete the OST file in the following segment.

Why Do Users Need to Delete Outlook OST File?

  1. The most common cause of OST file deletion is Synchronization errors. In such cases, the Outlook program behaves strangely and provides abnormal results. This issue can be troubleshot by deleting the local copy of Outlook i.e., OST files. But, users have a doubt about that is it OK to delete OST file.
  2. Sometimes, the system freezes too much and the reason behind that is overload space issues. This memory problem can happen due to the large size of Offline Storage files. Moreover, the huge size of the OST file leads to the OST file being inaccessible and having corruption issues. This will create problems like, Outlook stopped working, etc. So, it is better to delete the OST file and create a new one. But, most of the users have the same query i.e. “can I delete OST file without losing email messages?”.
  3. Another reason why users want to know what will happen if we delete the OST file is that the Outlook corruption can worsen due to inaccessible EDB files. In normal cases, when the users delete an old Outlook OST file, there are chances that the email messages will not be deleted. Users are able to synchronize the account with Exchange Server and retrieve the Outlook data back. But, when the EDB file is inaccessible, users need a solution to recover corrupt OST files. This problem can be resolved with OST to PST Conversion Tool. It is specialized to take backup files with ease.

How to Safely Delete Outlook OST File?

Do 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 the Offline Storage File into PST file format before going through the deletion process. The backup file enables the users to access offline file data from different accounts if the same Outlook profile is not available. Now, go through the below instruction to delete an OST file:

  • Close the Outlook program (if open)
  • Now, go to Start and type Run in the search box. Write the following command in the Run Window in order to get the offline data file location. Then click OK

Needs to Delete File

  • As soon as you click on OK, the location of the OST file is opened
  • Select the OST file that you want to delete and click on the Delete option. The following confirmation message pop-up on the screen

Is It Safe To Delete OST File?

  • Click on Yes to continue the process.

Once the Offline Storage File is removed from the system. You need to recreate a new OST file to let Microsoft Outlook work efficiently. But, before creating a new file, users want to know that is it OK to delete Outlook OST File? For this, make a new Outlook offline file with a different pathname and synchronize it with Exchange Server. After that, configure the Outlook account and start working with a new OST file. In order to do this, follow the below instructions:

Steps to Create New Outlook Offline Storage File

Once the old .ost file is deleted successfully, cross-check if it is still available on the Outlook account. Once you are confirmed, go through the following mentioned steps:

  • Close the Microsoft Outlook application
  • Now, provide a New Name for the Existing OST File. This ensures that the file name for each and every file is different
  • Again, Open the Outlook. You will receive the following error message-

What Happens If You Delete OST File?

  • Click the OK button
  • In the Offline Folder File Settings dialog box, click OK

Tip: With the help of this dialog box, you can change the path and filename of the OST file.

  • Again a Message will Appear on the screen;

What is Offline Data File?

  • Click Yes to continue the process
  • After that, go to the Tools menu, click on Synchronize-All folders
  • In this way, the New OST File gets Synchronized with the Exchange Server.

Note: Go and check out the solution to open another user OST file in your Outlook profile.

Concluding Lines

Email communication is very important for organizations. If this communication channel gets interrupted, users are unable to perform their work. In such a case, corruption in the Outlook .ost file is not permissible.

Therefore, in this article, we have discussed the OST file, why users delete an Offline storage file?, and is it safe to delete OST files?, and whether can users delete OST files without losing email messages? Along with this, we have described a solution through which users can repair OST file and safely delete an old OST file.


By Ashwani Tiwari

Being a Chief Technical Analyst, I am aware of the technicalities faced by the user while working with multiple technologies. So, through my blogs and articles, I love to help all the users who face various challenges while dealing with technology.