I would like to view some of the custom X headers generated by my e-mail server as part of the standard headers displayed (much like viewing the spamassasin headers (X-Spam-Level: ). Anyone know how to do this? I don't see any options in the configuration.

Not sure if right clicking on the email header and selecting View source will show you what you want. If it won't then see if the information is in a reply you get to an email you sent. I cannot see any way of getting information that has been added after the email has left kmail other than in a reply.

This is wishlist bug 16270. Add your votes here:
http://bugs.kde.org/show_bug.cgi?id=16270