hi, i need a solution for the exchange server.first i explain my servers setup. we have enterprise exchange server installed in additional domain controller. and i was installed exchange server 2003 and isa 2004 in child domains.these child domain belongs to another network. after installation of isa 2004 server i am getting an error messege "The server is not operational" "Facility: win32 "Id no: 8007203a" "Microsoft active directory-Exchange extension" i am able to create a user without exchange mailbox.while trying to create a mailbox for a user getting a error messege as give above. if this information is not sufficient i will give the detailed information for our network. thanks, robin pls find any solution for this.