Ok, I have installed and configured surfcontrol. Installed on a separate machine than my W2K/E5.5 mail server. My ISP is directing all mail for my domain to external address xxx.xxx.xxx.51. I have made changes in my firewall to direct all SMTP traffic (port25) to the surfcontrol box. Also, have enabled a one-to-one NAT mapping for xxx.xxx.xxx.51 to the surfcontrol box. This mapping was set previously for the exchange server. If this mapping is not present, the mail won't flow. Mail is going in and out, surfcontrol is seeing all of it. Here's my question: Outlook web access will not work now, and I cannot ping mail.mydomain.com or xxx.xxx.xxx.51 from an external client after changing the 1 to 1 NAT mapping. I do have internal DNS also. What am I doing wrong? Thanks, Chris