We recently upgraded to exchange 2010 from 2003. I setup a basic SSL cert instead of a UCC. I setup the cert to use mail.domain.com. Externally everything is working fine and no issues with cert. Internally on outlook 2007, 2010 and 2013 clients I am getting a "nonvalid certificate error". I tried installing the cert as a trusted CA, but that doesn't work.
I also changed the autodiscover url to mail.domain.com from server.domain.com, but no change with the certificate error.