"HTML Email" shouldn't exist, and doesn't for me. If you send me "HTML Email", it gets discarded, and you get a note back saying "don't do that". (If you send me an HTML payload along with plain text, I discard the HTML payload... see "A MIME is a terrible thing to waste".)

So, unless you know that your audience really really does want this, I'd suggest simply emailing a URL that someone can come visit, and that has your form on it.