After you have configured your Client Access Servers, and installed your organizations SSL certificate on IIS, you realize that users are not able to see the Free/Busy information for other users from Outlook 2003 or Outlook 2007.
Here are some of the symptoms:
When you try to create a new meeting request in Outlook using the scheduling assistant, you find that you are able to see free/busy information only for your own and not other users. Other users appear as ‘No information’. Under ‘suggested times’, in Outlook 2007, you find that it perpetually shows "loading". You may also receive a certificate error, concerning a name mismatch.
However, you are able to see the Free/Busy information for other users if you use Outlook Web Access (OWA).
The problem here is because of a certificate name mismatch. You have installed the certificate for your company’s webmail URL (webmail.company.com) on your Client Access server but your Outlook client is accessing it using the host’s FQDN, which results in the mismatch. If you have configured your internal DNS servers to resolve webmail.company.com directly to the CAS server (or the CAS NLB virtual IP), you can modify the InternalURL value by using the Set-WebServicesVirtualDirectory cmdlet. In the following command I am making the internalURL same as the externalURL.
Set-WebServicesVirtualDirectory -id:"EWS*" -ExternalUrl "https://webmail.company.com/ews/exchange.asmx" -InternalUrl "https://webmail.company.com/ews/exchange.asmx"
Before you do this, make sure your internal DNS servers are setup correctly to resolve webmail.company.com directly to the Client Access server(s). If you have multiple CAS servers in an NLB configuration, you will need to repeat the above command on all CAS servers.
Come back to Outlook and create a new meeting request with the Scheduling Assistant. Everything should be honky dory!