I would NOT use a mailto link. Not in this day an age. Spambot much? Definately a form that goes to a dynamic script. You put a mailto link and I guarantee that some spambot is gonna pick that up.
I do have a better solution. It was a silly little url traffic tool that I build for someone. It allows you to create custom links and url that you can put in a newsletter or something. Clicking on that link takes you to a page where a person can forward that page up to 5 people at a time. No email in page, no bots, no programming either.
Tell A Friend About This Page - that's the public demo.