How to Delete a Corrupt OST File?

OST is an Outlook data file, also known as an Offline Folder, that stores a synchronized cache of your mailbox items, such as emails, contacts, attachments, calendar items, etc., on your local machine. The OST file size grows as you send or receive emails and attachments. When it exceeds the recommended limit, which is 50GB for the UNICODE OST file, or the drive where the OST file is stored has low storage, it may lead to inaccessible, inconsistent, or corrupt Outlook OST files. Now it’s time t learn “How to Delete a Corrupt OST File?” without losing data.

Besides, virus intrusion, abrupt shutdown, force restart, system crash, faulty add-ins, etc., are some other factors that can cause damage to the OST file and render it unusable or inaccessible.

In such cases, users may encounter several issues, and errors in Outlook, such as send/receive errors, slow Outlook performance, delay in sending or receiving emails, synchronization errors, etc.

Outlook Users may also encounter errors, such as xxx.OST is not an Outlook data file (.ost), preventing them from accessing their Outlook account and emails. In such cases, they may also lose their mail items permanently.

microsoft outlook - How to Delete a Corrupt OST File

However, you can quickly resolve such issues and errors by deleting the corrupt OST file. This may sound easy, but you should be extra careful before deleting the OST file (even if it seems to be corrupt) and should never delete it in the first place if you don’t know what you are doing.

Deleting the OST file may resolve the issue but can also lead to permanent data loss if not done correctly.

In this article, you will learn steps to delete OST files properly, their impact, and resolve common Outlook issues caused by the inconsistent, inaccessible, or large-sized OST files without data loss.

What Happens When You Delete Corrupt OST File?

When an Outlook user deletes the OST file, a new OST file is automatically created the next time the user launches the Outlook client.

However, the OST rebuilds only when your account is still active and connected to the mailbox server. If the profile is deleted, disabled, or removed from the mailbox server, the OST recreation will fail, and you may end up losing all your mail items.

Steps to Delete Corrupt OST File

To delete a corrupt OST file, you can remove your profile from Outlook or manually delete it from the default location.

Delete Corrupt OST from Default location

Before deleting the OST file, take a backup to prevent permanent data loss. The steps are as follows,

  • Open Outlook 2013, 2016, 2019 or 2021, and navigate to File> Info> Account Settings> Account Settings.
  • In Outlook 2010, go to File> Account Settings.
  • In Outlook 2007, go to Tools> Account Settings
  • Click Data File and note the location of the OST file.

data files - How to Delete a Corrupt OST File

  • Open File Explorer and navigate to the path where OST is located.
  • You may also right-click on your profile name and choose Open File Location to locate the corrupt OST file

Open File Location - How to Delete a Corrupt OST File

  • Close Outlook and then copy the OST file to another drive or location for backup
  • After the backup, you can right-click on the OST file and choose Delete to delete the corrupt OST file.

Restart Outlook to recreate your OST file. This should resolve all errors and issues caused by the faulty OST file.

Alternatively, you may also press Windows_R, type %localappdata%/Microsoft/Outlook to open the default OST file location, and delete the OST file to rebuild it again.

Delete Corrupt OST from Outlook

If you use multiple accounts in Outlook and encounter issues with one of the profiles, you can use Outlook options to remove the profile and associated corrupt OST file from the system and then reconfigure the account in Outlook.

The steps are as follows,

  • In Outlook 2013, 2016, 2019 or 2021, go to File> Info> Account Settings> Account Settings…

Account Settings - How to Delete a Corrupt OST File

  • In Outlook 2010, go to File> Account Settings.
  • In Outlook 2007, go to Tools> Account Settings
  • Click the Email tab and select the user account you are encountering issues with.
  • Backup the OST file and then click Remove

Backup the OST file and then click Remove - How to Delete a Corrupt OST File

  • Click Yes when asked to continue. Make sure you have created the OST file backup before permanently removing it as it will help restore missing mail items.

Click Yes when asked to continue - How to Delete a Corrupt OST File

  • This will remove the system’s offline cached content, i.e., OST file.

Now, you can restart Outlook and configure the removed email account again to restore all mail items and start using your account.

To Wrap Up

Deleting a corrupt OST file in Outlook will remove all mail items from your system. Thus, it’s important to backup OST files before you remove or delete them from your system to resolve the corruption issue or error associated with OST file. In addition, after account restoration or OST recreation, you may find missing emails or mail items from your account. This is normal and happens due to synchronization issues caused by the corrupt OST file that prevented email items from synchronizing with the mailbox server. In such a case, you can use a Stellar OST to PST converter tool, to extract all the mail items from the OST file backup that was created and save them to an Outlook importable PST format. Once converted, you can restore all the mail items to your newly configured Outlook account and OST file, including the missing ones.

Nathaniel Villa
Nathaniel Villa