bug#73470: Rmail is not working with maildirs

[Eli Zaretskii <eliz@gnu.org>]

> From: Marc Coquand <marc@mccd.space>
> Date: Wed, 25 Sep 2024 15:20:51 +0300
> 
> I noticed that according to the documentation, rmail should work with
> maildirs, assuming you have movemail installed.
>  
> I made sure GNU movemail is installed and tried setting my maildir using
> set-rmail-inbox-list command. I set it to maildir://~/my-mail, which is
> the folder where my mail is stored. It loads without issue on other
> mail clients.
>  
> However, with rmail I get the error when fetching the mail saying "No
> mail.". I would expect it to load my email.

What happens if you expand "~" in "~/my-mail" and set the inbox to the
result?  For example, if "~/my-mail" expands to "/home/user/my-mail",
try using "maildir:///home/user/my-mail", per the documentation in the
node "Movemail" of the Emacs user manual.