When you set the script to send the email to a real address you answer, and then click on Reply in your mail client, where does it go? Does it go back to the poster? Or does it go somewhere else? If it doesn't go back to the poster, then you need to either use a different script, or modify a setting somewhere, so it does.
Autoresponders send email back to whomever sent the email. So it all depends who your script says sent the email.
Jeff