I just loaded Windows 8 RP on my EP121. I was never able to setup my exchange mail account on here in CP but expected that I could in RP. I still get the same error as before:
"Unable to connect. Ensure the information you've entered is correct."
My exchange server is Exchagne 2010 SP1. I have self-signed certs with my domain's CA for SSL. My e-mail address is the "Microsoft Account" address for my computer. The domain, username, and password works on OWA from IE10 on the same computer.
I also verified that it is not security policies that is blocking.