[Mew_old]

This exactly. Definitely a good start, OP, but this is flawed and highly vulnerable to spam, leading to HIGHLY slowed messages.

There'd be no "slowing" of messages, you'd just have a pretty full spam box if people decided to bot it and use it as an e-mail bomber.

ReCAPTCHA or another CAPTCHA alternative would be a plus too.

Actually, excessive outgoing messages delays sending. True story, seen it happen.

Perhaps a timer of 30 seconds between submissions.