it seems Certificate in Exchange2007 is more complicated. i've set up a Exchange 2007 SP1 server. Now i bought a single name certificate from CA. However, the server name is not equal to FQDN How can i do? i wish to use the cert in OWA, Mobile 6 and Outlook Anywhere. Can i rename the server to FQDN? seem not possible. Can i use self-signed certificate "internally" and use CA certificate at outside by OWA, Mobile 6 and Outlook Anywhere? Thanks. Tony