Software

On both systems open Exchange Administrator and check the IMS Connections tab. Path is Domain|Configuration|Connection. Make sure that the following is true; under "Transfer Mode" the radio button for "Inbound & Outbound" is active; under "Accept Connections" the "From any host (secure or non-secure)" is active. You may need to make many more changes in other areas of the Connections tab, i.e. Message Delivery. Therefore I recommend you getting a copy of a very good book called "Managing Microsoft Exchange Server by Paul Robichaux, published by O'Reilly. On pages 274-276 you will find everything you need to know about making connections between Exchange servers and other email hosts. Good Luck!

I'm not able to get a clear picture of your network but it sounds like you have two networks and each one has an Exchange server.
For proper troubleshooting, it would be important to know whether they are set up within the same Exchange Site and how they are connected (WAN, LAN or Internet). I'm guessing that they are set up as different sites and connected by Internet.

Based on that guess, is sounds like one Exchange server hosts the mailboxes and the global address list and the other server must be set up just as a messaging bridgehead server.

Since the server that hosts the mailboxes is also apparently the one with the Internet access, I'm wondering what the intended role of the second server is and whether your problem could besolved by pointing all the clients to the server with the mailboxes on it.

Incidentally, from a security standpoint, you usually want the server with the Internet connection to be the messaging bridgehead with all the mailboxes on the other server. That way, if some