If you're still not able to restore offline folder synchronization, the Microsoft Exchange Server service support file might be damaged. Replace a damaged Exchange Server support file Then, synchronize the offline folders again. Follow the steps in How to rebuild the OST file. If all the folders except the Inbox folder are synchronized, or if you're not able to synchronize the folders, you might have a damaged. In the Send/Receive Groups dialog box, make sure that the Perform an automatic send/receive when exiting check box is selected, and then select Close.In the Send and receive section, select the Send immediately when connected check box.In the Outlook Options dialog box, select Advanced.To synchronize all offline folders automatically every time that you're online and every time that you exit Outlook, follow these steps: If you have many items in the mailbox, and you haven't synchronized the offline folders for a while, the synchronization procedure might take more than 30 minutes. When the synchronization procedure starts, you'll see a synchronization status message in the lower-right part of the screen. On the Outlook ribbon, select Send/Receive, and then select Update Folder to synchronize one offline folder, or select Send/Receive All Folders to synchronize all offline folders.Select the folder that you want to synchronize.Synchronize the folders againĪfter you check the offline folder settings, use one of the following methods to synchronize the folders again. For more information, see Only a subset of your Exchange mailbox items are synchronized in Outlook. The item count for the offline folder depends on the Mail to keep offline or the Download email for the past setting.

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