Christian Funke wrote:
I think it is a bug in Kmail see https://bugs.kde.org/show_bug.cgi?id=292418 , it is supposedly fixed in 4.8.5
Thanks for pointing that out.
I should say that I now find KMail entirely satisfactory, after a somewhat bruising passage. The problem about top-level folders - I was the OP - is a very minor one, which I wouldn't even have thought of during the "crashing" days!