In Outlook, click Help > Check For Updates. If an update is found, download and install it. Restart Outlook. If the problem continues, click Help > Contact Support.
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Caution: The following procedure deletes any information that is not synchronized with the Exchange server, including your contacts' mail certificate. Emptying the cache replaces the contents of the folder with the latest items from the Exchange server. Before emptying the cache, you may want to back up your Outlook information.
• Make sure your computer is connected to the Exchange server. • In the navigation pane, Ctrl+click or right-click the Exchange folder for which you want to empty the cache, and then click Properties. • On the General tab, click Empty Cache. After the folder is empty, Outlook automatically downloads the items from the Exchange server. Related information.