[drupal-support] Sending HTML/Plain text e-mails from within drupal

My question is quite simple, only the answer gives me nightmares... :-( Is it possible to override the "User e-mail settings" - which are located at '?q=admin/user/configure' - so we can sent html/plain text e-mails with drupal? No matter if this could be done using a module, or whatever.. Any suggestions are welcome, but hacking the core code is the least option in my opinion.. Maybe, we want to see this in drupal as a feature? i am using the latest Drupal HEAD. (Gerhard, I know you think they are evil, and they are.. But, the client is King..) Stefan.