impove visual sorting interface (colored tabs or bins for categories)
improve visual sorting (using categories) or provide alternative to hierarchical folder list...a more intuitive graphical series of categories or actual folders would be great. This could incorporate flag/action status as well. Instead of making custom actions and/or sorting by color categories, categories would appear as either tabs in mail view window or visual "piles" of mail large enough on screen to physically drag and drop things quickly instead of using the category button in ribbon or the tiny custom action toolbar. make it feel more kanban!