Odd quirk in folder_format display

[Chris Green]

On Mon, Jun 21, 2021 at 10:15:45PM +0100, Chris Green wrote:
> I have quite a few levels of directories below my ~/mail directory.
> 
> For some reason when I navigate through some of them the numbers of
> messages are displayed whereas in others they aren't.
> 
... and of course I've now spotted the reason:-

    %m, %n, and %N only work for monitored mailboxes.

-- 
Chris Green