Make sure that you read through Toms "Publising a web server." I was getting the same error until I published the my server as a web server. It walks you through creating a seperate destination set other than the one for OWA and creating a seperate publishing rule. I am assuming that you ran through the process for publishing an SMTP server. You will also want to read the TACteam article that Tom has posted without you will get errors galore in regards to your exchange box. Let me know specifically what you have done so far I maybe I can help narrow your focus. I am cuurently running a SBS 2000 box, I am running SQL2000, ISA, Exchange2000 and IIS5.0 everything at this point is running great and all of my errors in event viewer are part of running all this on one box.