Recreate an offline Outlook Data file (.OST)

Some account types, such as Microsoft Exchange Server, use an offline Outlook Data File (.ost). This type of data file is a copy of information saved on your mail server. If you encounter problems with an offline Outlook Data File (.ost), the file can be deleted and recreated by downloading a copy of your items again. We don’t recommend repairing an offline Outlook Data File, so if your offline data file isn’t usable, you should recreate it.

  1. Exit Outlook.
  2. Open Control Panel, and in the Search Control Panel box, type Mail, and then choose Mail.
  3. In the Mail Setup dialog box, choose E-mail Accounts.

    Note: The title bar of the Mail Setup dialog box may contain the name of the current profile. To select a different existing profile, choose Show Profiles, select the profile name, and then choose Properties.

  4. Choose the Data Files tab, select the Exchange account, and then choose Open File Location on the mini toolbar.

    Note: A File Explorer window opens to the location of the data file for the Exchange account. The Account Settings and Mail Setup dialog boxes will remain open, behind the File Explorer window.

  5. Close the Account Settings and the Mail Setup dialog boxes, and then return to the File Explorer window.

    Important: Make sure you close these two dialog boxes before you delete the file. If they aren’t closed, Windows may display an error message about a conflict.

  6. In the File Explorer window, right-click the Exchange data file, and then choose Delete.

    Note: The next time you start Outlook, a new .ost file is created for the account.