I've gotten some really good answers to this point on a couple other topics and hope that I can get one more I have looked through the forum answers and have found a few that seem to come close to fitting the bill but nothing dead on. Here is my problem. I am a residential Road Runner customer trying to install zimbra behind a linksys router that's providing NAT for the actual server. Residential Road Runner is DHCP so my IP address resovles to a Road Runner domain. I signed up for, and have to renew, a dyndns account with my own domain and MX record so they seem to work.

My problem is sending AND receiving email at the same time. With DNS check enabled I can send out but can't receive. With DNS check turned off I can receive but can't send. I might have that reversed but the behavior is basically as described. I've tried adding entries into my /etc/hosts file for my dyndns name and local host with various configurations but I can't get send and receive to work at the same time. Is there a tutorial on how to configure this specific setup? Is there something that I am missing or could tweak without getting overly complicated? I don't currently have any experience with DNS servers and would like to avoid setting up an internal server solely for the purpose of "fooling" Zimbra.