First off, I've searched alot on this topic, and all the info I've found has been primarily geared towards integrating Exchange 5.5 organizations with 2000 and 2003. Anyway, I manage a multi-site, multi-domain network which is all part of the same 2000 forest. Everything is Windows 2000/Exchange 2000, and working fine. We were recently bought out by another company which is also a multi-site Windows 2000/Exchange 2000 domain. We aren't really interested in sharing any resources or control over our respective networks, but we'd like to combine our Global Address Lists to make managing our contact databases easier. We are on seperate NATed networks seperated by Firewalls which can sustain site-to-site VPN links. I was hoping for a simple software solution, but I'm guessing I won't be so lucky. Any idea what the simplest solution to my problem would be?