I'm curious if this design makes sense: Domain A has PC and user accounts. Domain B has exchange 2010 for users in Domain A. A is trusted by B. I'd like a user to be able to log onto a PC in Domain A, with an account in Domain A, and open outlook and have it authenticate to exchange in Domain B without any extra prompting for logon credentials. Whaddya think?

Can do, this involves an incoming domain trust to domain A from domain B, see 2003: http://technet.microsoft.com/en-us/library/aa997312(EXCHG.65).aspx 2010: http://technet.microsoft.com/en-us/library/aa998031.aspx -- Mike Burr