I have a SonicWall firewall appliance. It is set up to route people out to the Internet using NAT from the External interface's public address. I also have some other available addresses, so I set up a one-to-one NAT mapping to my Internal email server and then set up an access rule to allow WAN traffic (I presume Internet) to reach the public alias of the email server with SMTP & POP3. However, email is not coming in. Is there another way to do this -or have I done it incorrectly?