I haven't tried this, but...
I add my account to a Distribution List. I then open my Outlook and create a new rule. I choose "Start from a Blank Rule." I choose "Check Messages When They Arrive." I then go down the list of options and check "sent to people or Distribution List". I choose my Distribution List from the GAL. At the next screen in the Rules Wizard, I choose "Have Server Reply Using a Speciific Message". When the template pops-up, type your message in the body of the email and save it.
Again, I haven't tried this...but I think it might work for you.