Basic Exchange 2003 deployment connected/protected by an ISA firewall with one Internet IP address. We have another totally seperate Exchange envrionment for testing with a seperate AD and Internet domain on the same LAN. We would like to use the exisiting Exchange server connected through ISA to simply relay inbound SMTP email from the Internet to this seperate Exchange server. I am not clear as to what options are available to accomplish this. Any assistance would be greatly appreciated.