Apple Mail behaviour: can not create sub-folders

[Jan Bramkamp]

On 01.03.22 02:18, Joseph Tam wrote:
>
> One of my Apple Mail users recently complained his mail reader
> couldn't create sub-folders -- he could only create top-level folders.
> Playing around with this, I discovered that I could create folders (
> as opposed to mialboxes) *if* I specified mailbox name with a trailing 
> slash.
>
> Has anyone come across this?  Is this related to
>
>     https://doc.dovecot.org/configuration_manual/mail_location/mbox/mboxchildfolders/ 
>
>
> ?
>
> Joseph Tam <jtam.home at gmail.com>

Which path separators did were used?