Outlook has one ribbon displayed when the email index is shown, and a different ribbon when a MailItem is open. I managed to add buttons to the Miscellaneous group in the ribbon for the index, via File -> Options.
Can I customize the ribbon for a MailItem via File -> Options?
Can I do this via VBA? Can this VBA be executed automatically at launch time?
I managed to do it via File -> Options. It was very simple, I had to access File -> Options from within the MailItem instead of the main window.
As per this, it apparently cannot be done via VBA.