

You can delete and recreate the OST file. Read the Support Center article on How To Create, Compact, Repair Or Delete Offline Folders (How To Rebuild OST File) for instructions. If there is an improvement in Outlook performance in Online Mode, it means the Outlook local cache file (.OST) is corrupted. Read the Support Center article on How To Enable Cached Exchange Mode In Outlook for more information. Run Outlook in Online Mode: go to File (Tools) > Account Settings > double-click on Exchange email address > uncheck Use Cached Exchange Mode > save the changes > restart Outlook. If the Outlook status is Working Offline, open the Send/Receive tab and disable Work Offline option. Sometimes Outlook may go to Work Offline status when there are intermittent issues with the Internet connection
