Just discovered a new hotkey in Outlook that I previously did not know about. When typing names in the To field you are often presented with the drop down list of previously resolved addresses from the Outlook local cache. This cache is stored in a file usually called outlook.nk2 in you userprofile directory tree. But if you have not previously used the address and want Outlook to try to resolve it you can press CTRL+K. This is the same as pressing the Check Names button on the toolbar.