Mail app design

I was thinking the other day about the current mail apps for mac. There are good ones and bad. I really like the direction of Airmail and a few others. I had bought Sketch 3 the other day and by the way I'm loving it! My first project/concept I wanted to do was designing a mail app. I thought about simplicity and I also like the app Tweetdeck. I haven't finished the design yet but this is a preview. Check out the full shot!