I have a new setup of exchange 2010 and everything seems to be working fine except I cannot connect external outlook clients. Internally no problem and OWA works everywhere. I have run some tests using www.testexchangeconnectivity.com
and the problem area seems to be with the autodiscovery part. This is for a hosting implementation (hopefully!)
Checking Host autodiscover.DOMAIN.com for an HTTP redirect to AutoDiscover
ExRCA failed to get an HTTP redirect response for Autodiscover.
An HTTP 403 forbidden response was received. The response appears to have come from Unknown. Body is: You do not have permission to view this directory or page.
I am using a UCC certificate on the CAS server. This is going to be a hosting solution, so the domains of the clients are not default. I have added an autodiscover A record for the client domain to point to my CAS server.