I have set this feature up a billion times but this time I am perplexed. I have set up the details in Outlook correctly and also in SBS2003 gone to Internet Setup and setup the certificate with the correct IP address. I have OWA with no problem but Outlook will not work. I have installed the certificate by going to IE in Admin mode (Vista) and installed the certificate in the trusted directory. I restarted IE and the cert is installed fine (according to OWA). Outlook still wont work it just keeps asking for the Username and password. It's driving me and my client mad!