I use a text-only email reader called mutt. When I sign up for updates and what-not, I tell them that I want the text version of their email. Most mailing applications will, at the very least, send multi-part messages so you have the option. Others decide to send HTML-only email.

So, assuming that the vendor wants to make their messages available in HTML & text for maximum effect, I’ll send them a quick message letting them know what’s wrong punctuated with an offer to help them sort it out. I’ve gotten a favorable response more than half the time. Good average.