There is no way see what shortcuts are available in Thunderbird. You have to go to a support website to even find out what shortcuts there are. To configure them you need to use third party add-on that is not even available from add-ons.mozilla.org. That apparently doesn't even work anymore. I'm using Thunderbird 45.2.0. Some earlier versions at least showed you what the shortcuts were. Now you have to go to your web-browser and read a mile long page that may or may not list the shortcut you are looking for in a language that may or may not match the one you are using. It would be far simpler to have them listed in menus, in popups that appear when you hover over a button, and in a configuration dialog that lists all shortcuts. Not all of us users want to/can use a mouse for every little task. So this is a significant usability issue. There are numerous bugs about this on bugzilla (201011, 57805 etc.). Some of which have been open for 16 YEARS. Please, please, please fix this. Assign a milestone that this is fixed by and it will get done.