Most mail clients won't execute javascript, though.
Very interesting. I suppose it would only affect browser based email clients, but a lot of the non-tech-savvy people I work with use the web mail client exclusively, so that is definitely an issue.
I'm still baffled why I was downvoted into negative territory for my original comment.
Don't worry too much about it. I say incredibly useful and 100% correct things all the time and people still downvote me sometimes!