> Stupid people need stupid questions...  I hang my head.  Unfortunately, I
> can't now try it because KMail-trinity now crashes as soon as I try to open
> it.  I need to get back somehow to square one with it.  But when I do, I
> shall immediately try your suggestion - and kick myself hard again.
>
> (The obvious thing to try first is reinstate the default in kmailrc.)
If I were in your situation I would try to remove all KMail's config files:
~/.trinity/share/apps/kmail/*
~/itrinity/share/config/emaildefaults
~/itrinity/share/config/emailidentities
~/itrinity/share/config/kmailrc*
~/Mail (or any other directory that contains your emails).
By removing I mean of course moving them to different location, so they can be restored. I would 
hope that KMail will simple recreate those files and then you could try to import emails from old 
KDE3 directory.

I don't claim that this will work, but that's what I would try.

Jan