I'm pretty sure it's still not possible, but I haven't looked into it for a while. Can I add a form to an email, instead of linking off to a different page? Not sure where you'd go when you click submit, but just wanted to check if it's become possible with updates in technology.
Last time I tried it out it was about the same, a few email clients would let you and others would break it or strip it out. Your safest bet it still to link to a form on your website rather than including it in your email. If you do include one in your email I'd really suggest including a link to a web based one as well for anyone who can't use the email based form.