OK, I have this problem that is driving me crazy. I have an NT 4 box running Exchange 5.5. On certain domains it tries to resolve and then send email to, it appends our domain to the end of it, which resolves to our web server and sends it to that server. Luckily this server is running the SMTP service and we have turned on forwarding so the mail goes out ok. Before we did that (turn on forwarding) we would get a 550 host unreachable error on our outlook client. Most email recipients resolve ok but a few here and there the server attaches our domain to the end (so it looks like conseco.com.ourdomain.com for example) and then sends it to the outside server. This is because our domain.com resolves to this outside server. I need to resolve why this is happening becuase the server is going to be going away soon. Anyone have any ideas? We are also running Mcafee Webshield. I'm not sure if this is the culprit.