Hi All, I've re-read the articles on ISAServer.org and decided to add back in the capabilities to utilize Outlook clients over RPC to connect to my exchange machine. I run a back to back network. All machines are w2k boxes. I've not yet moved all over to windows 2003. My DNS machine in the DMZ hosts many sites and has a different Name then my DNS server behind my second firewall. My external ISA box has the message screener running and forwards all SMTP mail to a relay box. So, I setup the Exchange RPC rule to point to my internal ISA machine. I'm not sure if by pointing to the different sources has any affect on connecting with outlook client. SMTP mail is arriving as setup. I know that for the blaster and sasser type scripts it disables access to ports 135(outbound) and 445. What is the best way to trouble shoot this type of setup? I'm unable to connect from an external outlook client, message is that global address book not available? And can't find exchange. I don't' see any particular messages in the log files to pinpoint connectivity issues. Thank you, Joseph