This change was required on the Exchange 2007 Client Access Server (CAS) in order for clients to accept the wildcard certificate that through the Autodiscover Service (AS) for Outlook Anywhere.

Command:
Set-OutlookProvider expr -CertPrincipalName:"msstd:*.domain.com"

Verification:
Get-OutlookProvider |fl
Look for the property EXPR called CertPrincipalName