HI, I plse help ! I have my exchange front-end svr in the DMZ and my back-end svr is behind the firewall.when i disable ip packet filtering and firewall services it works. should i need only to apply ip packet filter to the following ports: 80/TCP,143/TCP,110/TCP,25/TCP,389/TCP,3268/TCP,88/TCP,88/UDP,53/TCP&UDP,153/TCP,1024/TCP and 445/TCP Or i need to create protocol definition and server publishing. I have made a test using telnet svr, i have create an ip packet filter for the telnet port but invain. with thanks