If you are away for period and no body is there to respond then auto-responder is a good tool but you explain that once you back you will contact, leaving important tips or some one responsible address to contact as phone number or E.mail . But leaving the system work blindly you are just leaving bad impression about you work efficiency. so if you use if you have to use it wisely for limited period, and go back to your customer once they leave their messages and questions as you come back.