Kristin,
"Without using a Handler" looks to me to be the sticking point. The issue is further complicated by the fact that I assume the address required is actually in the body of the email?
I would perhaps have another system process the email and then pass it on to PureConnect. That system could perform the auto-response for you? YOu could even potentially modify the website code to do this in these situations.
Sorry I can't be of more help.