When the mouse hovers over folder names in the navigation pane or folder list, Outlook pops up the full name in a tooltip. This tool tip often obscures the folder below and provides little useful information for most users. Can it be turned off?
 
There is not a switch or option to turn it off, but you can prevent these popups if you either use shorter file names or make the navigation pane section wider – the tips only display when the folder name is too long to be completely visible.