Especially in the notmuch+maildir interface, it would be nice to have a means to access the files in the maildir folder structure that represent a given message. This information could be shown in the headers of the message view, for example, or in a pop-up like the envelope's.
It would be even nicer to be able to operate on those single files (deleting all but one of them comes to mind).
I think this might be actually done, ~inwit?
Solved with the {{.Filenames}} template.