I have Mint OS and am trying out Kmail (stand-alone).

Is there an index or toc in kmail, where one can browse a list of open messages/folders/windows, navigate between them, and manage them (open, close, ...)? I guess one can open messages from the main window, but browsing, navigating, closing are not linked as far as I can tell. (?)

The main menu (with global settings and options) in the main kmail window got shut off somehow. How do I get that back; right-click doesn't seem to show the way?

Try Ctrl-M to bring up the menu again.