The Message Viewer window in Mail on my Mac has suddenly disappeared. When I start Mail I get the menu bar and I can also write new mails - but the main window (Message Viewer) is somehow gone. Trying to make it visible through the menu bar (Window - Message Viewer) does not help, restarting the computer does not help, fiddling with the view options in the Mail preferences (to which I can also get) does not help.
What can I do to get the Message Viewer window back?
What can I do to get the Message Viewer window back?