Mail browser has 20+ viewer windows open but can't close them all, even with a force restart When I click show all viewer windows, they pop up on the bottom and allow me to pick one by one to close them. Is this my only option to close them all?
Command + Option + W closes all the Windows on the app. 

One may also click on File menu at the top, and hold Option key to find the Close all option to close all windows.