Can your POP3 Server software provide publicly accessible mail services if my server machine sits behind a DSL Router/Firewall?
Yes. This is typically accomplished via “port mappings” at the Router/Firewall, which has your publicly accessible “external” IP address. Your server machine has a private “internal” IP address. The port mappings essentially pipe connections and traffic to/from the external IP address at the router to/from the internal IP address at the server. You configure your services to listen on the internal IP address. Presumably your DSL service provider will provide your external DNS services, but you must also run DNS Server locally to provide local area name resolution on the private portion of your network.
