Hello - we're working on preparing for a 2003 to 2010 Exchange migration from a physical 2003 server, to a virtual Exchange 2010 (on Windows 2008 R2) server. what's been done so far is installed 2010 Exchange, updated it to SP2 / Rollup 7, and have verified connectors are in place. We're wanting to verify that 2003 users can send and receive from 2010 users on the new server, so have created a new user on the 2003 side, as well as a new user on the 2010 side. Those created successfully, but are having trouble just logging on to either user now with Outlook 2010. We get a "user match cannot be found" error. I checked to see if I could make a match to an already existing user on the 2003 side, and that works. it's only new users that are created that can't seem to be found. Could this be an AD replication timing thing? Just looking for some ideas.