So just randomly a few days ago Mail stopped working. I have it setup with my account fine. It was working sending/receiving mail for 2 weeks. Then just one day I open Mail, it opens, but all the windows are blank, like I've never had any Mail. Then the little balloon comes up and it never fully launches. I open Force Quit and it always has Mail in red with the (not responding) next to it. I Force Quit, reload it, same problem. I have all the latest updates installed, including the Mac Mini SMC firmware updater. Although this problem existed before I updated the firmware, so it can't be because of that.