Dear Members, Thanks for your valuable articles and it has helped me in implementing many projects. The exchage front end server is connected to pix515 dmz port and ISA 2004 outside interface is connected to pix inside interface. ISA 2004 Insiade interface and domain controller and exchange 2003 backend server are in the same subnet. can i know the list of ports to be opened in pix so that exchange front end server can communicate with exchange backend server,domain controller. Internet user shall access mail using OWA. POP3,imap will be disabled. Is ther any means so that i can upload the network diagram? appreciate if you can help me and other steps i need to carry out. Regards, Prashanth