The nomx story reminds me of a conversation I had with a friend a few weeks ago. He wanted to set up a mail server at home using a RasPi and grudgingly accepted that it's not a good idea after I told him that:
a) All dynamic IP ranges are blocked in DNSBL
b) His ISP explicitly forbids non-business customers hosting publicly reachable servers
c) All sane customer ISPs block port 25 outbound
d) He can't provide the uptime for anything critical.