Ok I am attempting to test my autodiscover service in a exchange 2003 and exchange 2010 coexist environment. I have TMG as my reverse proxy back to my cas array. I have a rules in TMG for legacy.domain.com and exch2010.domain.com to publish OWA and Exchange active sync. Legacy points to my exchange 2003 FE server and exch2010 point to my exchange 2010 CAS array. If i want to test autodiscover and the mailbox is still on the exch2003 server should my publishing rule point to the exchange 2003 front end or to my new cas server. Also will the autodiscover service on the TMG server that points to my exch2010 cas array return the info for a milbox that is still on the exch2003 server? Thanks.