I need some newbie help.I've got a situation like this: (fixed ext. IP Address)Router NAT(192.168.32.1) >> (192.168.32.106)external [ISA 2006] internal (192.168.4.106)>> (192.168.4.105) Exchange Server 2003. Exchange server is running on a SBS 2003 box which also servers as AD host and DNS server. I have tried to follow http://www.microsoft.com/technet/isa/2006/deployment/exchange2003.mspxto publish the SMTP server but I can't configure it so that I can telnet into the exchange server using the external domain name for the MX record and likewise, I can't recieve emails addressed to mailbox@public_domain_name.com. - I can ping mail.public_domain_name.com from a workstation on the local network (192.168.4.x). - I can ping the LAN interface (192.168.32.1), and the external NIC of the ISA server (192.168.32.106) from the local network (192.168.4.x). - I have Internet access from the local network through the ISA proxy web server. The following appears in the referenced article: "External Network Listener IP Selection -- Listen for requests on:Select Specified IP addresses on the ISA Server computer in the selected network. Select the appropriate IP addresses and click Add. Important: The selected IP addresses must match the MX record IP addresses." I'm obviously missing something here, but how can the specified addresses on the ISA server computer match the MX record IP if the MX record is an Internet IP and the external address of the ISA server is a local, non-Internet, IP (192.168.32.106). When I select "Specified IP addresses on the ISA Server computer in the selected network" the only address available in the list box is the external NIC address of the ISA server. How do I set this up so that my incoming Internet mail can gain access to the SMTP server on the exchange server through the router and through the ISA 2006 server? Thanks in advance for the help. Jay