Offline Folder files (.ost) have a default location on a computer. Sometimes you may need to change the default location in order to manage mail in Outlook or manage disk space on a computer.

To change the OST file location on the Outlook 2007 - 2010:

  1. Exit Microsoft Outlook.
  2. On the desktop, click Start > Control Panel.
  3. In Control Panel, double-click on Mail.
  4. In the Mail Setup – Outlook window, click on Email Accounts.
  5. In the Account Settings window, select Microsoft Exchange and then click on Change.
  6. In the Change E-mail Account window, uncheck Use Cached Exchange Mode, and then click More Settings.
  7. In the Microsoft Exchange window, click on Offline Folder File Settings.
  8. In the Offline Folder File Settings window, click on Disable Offline Use.
    Note: Disable Offline Use might be inactive. To re-enable it disable Cached mode and restart the Outlook. Read the Knowledge Base article on What Is Cached Exchange Mode In Outlook? for more information. 
  9. Click OK to return to the Microsoft Exchange window. Click on Offline Folder File Settings again and click on Browse to change the location of the Offline Folder, then click on OK.
  10. Return to the Change E-mail Account window, check Use Cached Exchange Mode and then click on Next.
  11. Click on Finish to save changes and close the window.

Important: Outlook 2013/2016 does not allow to change the .ost file location. Read Microsoft article on how to change the .ost file location for more details and further troubleshooting.