Mail Stopped Woking in Sierra
Installed Sierra on late 2009 27" iMac. Most seems fine but when Mail tries to load, window will not load and none of the navigation menus are available (really, none at all!). Reinstalled Sierra--- same problem. Kind of disappointing to have to spend any time to sort out this basic computer application.
VIN,iMac (27-inch Late 2009), macOS Sierra (10.12)