I have a feeling I have not added the correct domains to my SSL cert for Exchange 2010. External clients are unable to connect to outlook anywhere. In external outlook, I get a prompt for username and password but I continue to be prompted for username and password even after entering correct credentials. I can successfully navigate to https://domain.com/rpc/rpcproxy.dll from an external browser and login successfully(blank page is loaded). Any help would be greatly appreciated!