Found mail message in Outlook for Mac, but want to find the source folder
The internal search for Outlook:Mac 2011 is Spotlight search.  

When you search from Spotlight outside of Outlook:Mac, and you select a result, that email is opened in a new window.  The title of that window is "subject - folder".  This isn't perfect, since it only tells you the name of the parent folder.  If you have a deep folder structure, or if you reuse folder names, you'll have to figure out where that particular folder lives.