In our environment we have 5 separate GroupWise systems. All with their own separate trees and connected to each other using "External System Synchronizations". I'm trying to coordinate all of the external MTA upgrades to GW8 sometime in the next few months. Are there any compatibility issues with running in a mixed GW8 and GW7 environment as far as external systems are concerned? Or do we need to upgrade them all at the same time?