I have recently installed a new Exchange Server on a new Server PC at a different location. The old Exchange Server was on the same machine (and network and Windows domain) as an IIS 6.0 Web server. After moving to the new Exchange Server (I left the old one running to catch mail during the time it takes all DNS records to be updated), most mail went to the new Exchange Server, but mail that originated within the web server still went to the old Exchange Server. (After the change, I created a new A record at my ISP associated with "mail.whatever.com". I then created an MX record with the name "mail.whatever.com" pointing to the new Exchange Server site. My question: Is there some place where DNS names are cached (other than the obvious DNS cache on the local Web server/Exchange Server machine) that is not obvious? Or is there some shortcut optimization that IIS does with Exchange where it tries to outsmart me?