Please don't send HTML email, there is almost never a scenario when it is necessary. All it does is create larger emails, have redundant information (most HTML emails also send a plain text counterpart), make reading email more difficult (especially if you are using a terminal mail client or are visually impaired), and allow for obnoxious email styling. HTML Email, just say NO.
It's very obvious you've never used an opt-in email list to build and grow a commercial business.
You think Groupon (and the ilk), or Newegg, etc, would see the huge returns from email they do if they were sending out plaintext?
The only thing that really bothers me about your posts, though, is that you try to say things with such a tone of authority. But you just don't know what you're talking about.