As you know, the Imbox is divided into two sections: New for You on top and Previously Seen down below. And while New For You is something you always want to see, some people feel like Previously Seen is a bit of a distraction. It's nice to have recently viewed and sent emails close at hand, but for some, staring at the them all the time is a bit much. We hear you.
This is where Cover Art comes in. Now, you can put a visual cover over Previously Seen. A pretty picture, a pattern, a photo of your choosing. It's entirely up to you. It'll spruce up your Imbox, calm things down, and hopefully make you feel good every time you see it.