Josh Allen expounds on the irrational hate for HTML email, such as this comment from Dan Lyke.
I tend to not mind HTML email in Eudora, since it only uses a subset of HTML: no images and whatnot. Unfortunately it does pay attention to font sizing and coloring, so half the time back when I used strange Windows colors, I couldn't read HTML email for it being black on dark, dark grey.
I wouldn't mind HTML email at all if it were, as I suggested for web syndication feeds, only a particular module or two from the XHTML Modularization spec. You'd get your <p/> and your <blockquote/>, but not your <font/> or <img/>. <a/> is all right, though.
Basically, I don't mind HTML in email as long as it's for meaningfully marking up mail. I mind HTML in email when it's an attempt by the author to control my reading experience by making the font too large or too small or the wrong color.
