So I followed the whitepaper. Installed AD on a Server 2008 R2 machine (at a 2008 Forest and Domain level). Then I installed Exchange 2007 SP2 Mailbox and Client Access roles on a Server 2008 x64 machine. Then I installed BES 5.0 on a Server 2008 x86 box which worked fine (pointing to the Exchange 2007 SP2 server). I then installed all 4 roles of Exchange 2010 on a Server 2008 R2 x64 machine. Now here is where it get's interesting, BES works fine. However, I could not send or receive mail and had to install a Hub Transport Role on the Exchange 2007 SP2 server for send/receive mail to work even though I had a perfectly good HT 2010 server that was configured correctly. 2007 couldn't see my 2010 Hub Transport Role. Also, I can only use OWA 2007, not 2010. Has anyone had these issues?