Thanks for reading this, I need a little help.

I have one main server and a firewall/modem. My firewall has always been setup to assign the server the public IP address and redirect all traffic to the server. For security reasons I wanted to change that, so I re-configured my firewall to assign the server a private IP address and block all traffic. I then created a rule for all zimbra ports, so all of the mail ports are open.

But after the change to a private IP address I can no longer receive any mail. It all appears in the mail queue under deferred. The error is "mail transport unavailable"

I can send mail no problem but cannot receive mail.
Any help would be greatly appreciated!!

My server is the latest zimbra open source on Ubuntu server 8.04.