use Mail.app as it just doesn't fit into my workflow. However, if I did use Mail I would most certainly take advantage
of the 'Smart Folders' feature to make my life a little easier. Mac Geekery taken it upon themselves to clear up some misconceptions about Smart Folders
(focusing mostly on the fact that they aren't really folders at all) and make us all aware of what is really going on
under the hood.
Worth a look if you have ever wondered about how smart those Smart Folders truly are.