In Rants and Revelations: Remind me again why I do this? I ranted about the abuse I get because I ask people to not send HTML email to my mailing lists. The usual rejoinder, after they finish being rude or calling me unprofessional or a luddite is to say “Where does it say I can’t send HTML?” So as of right now, it says it on the list info pages. Check out the LUGOR newbie SIG page for an example.
Note that I word it as a request, not a demand, and I even link to a page that shows you how to configure a bazillion mail clients to not send HTML mail. Damn, I’m too nice.