If you are getting a certificate security alert with the following error when you open Outlook 2007.

“the name on the security certificate is invalid or does not match the name of the site”

This is because the name on the server and the name on the certificate is mismatched. To resolve this, you will need to type in the following command in Exchange Message Console.

Set-ClientAccessServer -Identity CAS1 -AutodiscoverServiceInternalUri https://cas1.domain.com/autodiscover/autodiscover.xml

Set-WebServicesVirtualDirectory -Identity “CAS1\EWS (Default Web Site)” -InternalUrl https://cas1.domain.com/ews/exchange.asmx

Set-OABVirtualDirectory -Identity “CAS1\oab (Default Web Site)” -InternalUrl https://cas1.domain.com/oab

Set-UMVirtualDirectory -Identity “CAS1\unifiedmessaging (Default Web Site)” -InternalUrl https://cas1.domain.com/unifiedmessaging/service.asmx

You can also use the Get-ClientAccessServer command to get the current settings on the server.

Once you have typed the above commands into the server, make sure to restart the IIS service. You can do this with the IISRESET /NOFORCE command or restarting the IIS service under the IIS Management console.