OST, also known as Offline Storage Table, is an offline folder file used in MS Outlook. It enables offline mode within Outlook, allowing users to create and save changes while offline and later synchronize them with the Exchange server. This functionality proves advantageous in situations with limited or no connectivity. OST files are recognizable by their .ost file format, which permits users to work with their offline inbox and outbox locally. These changes are synchronized and reflected in the server once the system is reconnected to the internet.

How to disable OST file?

While OST files offer several benefits to users, there are instances when people may wish to disable them due to various reasons. Here is how you can disable OST files:

  1. You need to perform a synchronization process first. Synchronize all of your OST files. For this, you need to go to the particular folder which you want to sync. Go to the tools menu and select Send/Receive option and finally select the folder. If there is more than one folder, then after clicking Send/Receive and then click on Send/Receive All option. If it is a group which you want to synchronize then click on Send/Receive and select the name of the group.
  2. Next, you need to click on Tools menu, click on Email Accounts and click on View or change the existing email accounts. Finally, click on Next.
  3. On the next window, click on Microsoft Exchange Server and click on Change.
  4. In the dialogue box click on More Settings.
  5. Now you need to click on the Advanced tab and then click on the Offline Folder File Settings
  6. Now select the Disable Offline Use button.

If your Outlook is set to prompt you for online or offline mode when offline mode is enabled, and you wish to change this behavior, follow the steps below:

  1. Go to the Tools menu, click on Email Accounts, click on View or change the existing email accounts and click on Next.
  2. Next, in the Microsoft Exchange window click on Change.
  3. On the next Step, you need to click on More Settings and select the General tab.
  4. There you will see an option, "When Starting" select Automatically Detect Connection State.
What if instead of disabling OST file you have accidentally deleted them?

If you've unintentionally deleted OST files, there's a solution for recovering your data. I recommend installing the Kernel for OST to PST Converter tool on your system. This software is designed not only to recover deleted OST data but also to restore missing or deleted Exchange mailboxes. After the restoration process, the software offers a preview of the recovered data.


OST files play a crucial role in MS Outlook, serving as a working medium when there is no internet connection. In this blog, we have discussed how to disable OST files if they are no longer needed. However, if you wish to permanently delete them, you can do so. Keep in mind that if you ever need to recover any removed or lost data, the OST to PST conversion tool is the best solution.