Some ISPs are stricter than others about not running servers on residential internet accounts. Sometimes they just plain block ports, especially for email so th

Some ISPs are stricter than others about not running servers on residential internet accounts. Sometimes they just plain block ports, especially for email so they don't have to deal with virus-laden spam relays on customer's PCs. And if you're on cable, you might only be guaranteed 5 mbit/s upload, and actually using that much all the time would contribute to congestion on your node (shared by your neighbors).