Networking & wireless: New SMC7004VBR router stops local access to email server etc

New SMC7004VBR router stops local access to email server etc

I've sucessfully replaced a burnt out router with an new SMC to gain internet access, and written the NAT to allow the email and HTTP server to be accessed from outside. This works. However, machines on the local network are now not fully linking with the server. I can see the connection to the email server, but no mail is downloaded to the client and eventually it times out and closes the connection. I've not been smart enough to spot where the configuration is for this. My past D-Link router had a LAN firewall ?bypass which allowed this traffic. Clearly this problem hobbles our use of our email server, with the only way to see incomming email via a 3G!

Is there a setting I am missing, or a workaround?