In order to run a Mail Server behind WinRoute it is necessary that you create at least two Port Mapping entries - one for the SMTP protocol (which runs on port 25) and one for the POP3 protocol (which runs on port 110). This will allow other SMTP servers to reach your SMTP server and also you will be able to pick up your email by POP3 from the Internet. Some mail servers may use additional ports for web mail or IMAP, in which case you will need to make additional port mappings for those protocols.
SMTP protocol:
Protocol: TCP
Listen IP:
Listen Port: 25
Destination IP: enter the IP address of the SMTP Mail server (e.g.192.168.1.10)
Destination Port: 25
POP3 protocol:
Protocol: TCP
Listen IP:
Listen Port: 110
Destination IP: enter the IP address of the POP3 Mail server (e.g.192.168.1.10)
Destination Port: 110