Hi! I repeat my questions and add other questions: 1) Is there any connection between RPC Proxy server (front-end Exchange) configuration and MS Internet Explorer on server? If yes, what? 2) Is there any connection between ISAPI extension and RPC Proxy server? If yes, what? 3) Is there any connection between Tunneling TCP/IP protocol and RPC Proxy server? If yes, what? Added questions: 1) Which function has ExchangeAppPool in IIS virtual server on front-end Exchange? 2) Must I use only ExchangeAppPool instead Default? Best Regards Mustafa