I don’t know why you can’t change the header settings within settings/configure kmail or something. I could not even find any documentation about changing the header settings, but discovered this by trial and error.
Thanks for the tip about header-style.
OK, the results I get are with KDE 2.2.2, kmail 1.11.2. If you open a particular email, the view menu has a header option which is not persistent. The view menu on the main page has no such option. I will see if I can upgrade kmail. Thanks for the info.