The best advice I've read for this is to treat support emails as bug submissions. Questions about your company mean you don't have sufficient documentation, he

The best advice I've read for this is to treat support emails as bug submissions. Questions about your company mean you don't have sufficient documentation, help, user interface, etc etc, and work should be put into shoring up those areas. Obviously this idea doesn't eliminate all support requests, but I imagine it would reduce the deluge over time.