From: New York
Problem understanding how to configure TCP/IP for both my Exchange Server and ISA.
On my Exchange server, I set the default gateway to point to the ISA server. This default gateway normally points to an interface on a router which connects 7 remote offices.
On the ISA server, the internal NIC was set with the IP address for this particular subnet, appropriate subnet mask and no default gateway. The external NIC is configured with IP’s associated with our ISP, including the ISP’s DNS servers.
Everything worked great—was able to send and receive email with no problems.
However, any computer outside of the subnet where the ISA server and Exchange server reside are not able to communicate with either the ISA server or the Exchange server.
For example, all PC's located on the 10.1.1.0 network were able to send and receive both internal and external mail. PC's located on the 10.1.5.0 subnet were not.
Once I put the default gateway on the Exchange server back to the router interface, then no email could be sent or received.