We have an existing 2003 exchange environment and when we went to upgrade we found out our config is not supported.
So we built a new domain (domain2) and built a 2010 exchange environment with a mailbox server, a hub transport, and a CAS. Everything works great from outside the network. We set up a two way trust between domain1 and domain 2
The issue is when a user in domain1 tries to connect to the new exchange server. It gives a variety of different issues. We have tried to connect Outlook to the AD server instead of the CAS, and that sometimes will work for the name resolution, but then Outlook crashes later. It seems to be related to accessing the address list.
If we log into the exact same machine as a local user (no domain) it works just like it does from outside.
There is a hotfix from MS that is supposed to deal with a lot of 2010 issues, but I wanted to see if there was something with the trust that may be causing this issue.