The exchange auto-responder isn't smart enough on its own to prevent mail-loops so if you set it up without a limit it would respond to an auto-responder that responds back and respond again, etc. You could forge an email from one responder to another and get Exchange servers to DOS themselves.
There is a way to turn off that protection but sooner or later that will buy you only grief. There are plenty of marketing tools that add this functionality and help track it and de-bounce duplicates and so forth. It is worth investing in one.
Here is a FAQ on setting up the AutoResponder: http://www.dharwadkar.com/weblog/msexch_tip02 that you can use in the meantime.
I've noticed that the reply-to list seems to get reset when you turn your message off and back on. I've never tested it deeply but I bet you could run a powershell command like this every night and turn the responder off and back on to get fresh replies once a day.
Set-MailboxAutoReplyConfiguration -Identity YourListOrMailBox -AutoReplyState disabled
Set-MailboxAutoReplyConfiguration -Identity YourListOrMailBox -AutoReplyState enabled
That's untested, mind you. Worth trying if you're hurting the budget and can't buy a responder with features and tracking and such.