@rsenio
Thank you for the reply, that's the same package that I used. The issue was it took me a bit of research to find that:
1. The location of CDO.DLL and EXMAPI32.DLL (previously MAPI32.DLL), has been changed from %SYSTEMROOT%\system32 to C:\Program Files (x86)\ExchangeMapi\.
2. The MAPI32.DLL file has been renamed to EXMAPI32.DLL.
It wasn't clear to me on the MS site, that this change had been made.
My BES 5.0 test environment, on ESX 3.5 update 3, is working like a charm.
I've also set up the new High Availibility for BES and database mirroring:
BES - Server 2008 64-bit (2 total)
Primary
Standby
MS SQL Server 2005 - Server 2008 64-bit (3 total)
Principal
Mirror
Witness