Hello, Maybe it is a really stupid question, but I always worked with servers of customers that always used their own smtp to send email. Now I want to configure a server to use it's ISP's smtp because of the following error they received: www.*****.com #4.0.0 smtp;451 62.195.5.92 blocked. Your /24 netblock has more than 9 listings at http://dsbl.org Use your ISP's SMTP server to send us mail or ask abuse@xxxxxxxxxxx for removal. Can somebody tell me in short where I can find this with in exchange? Apparantly they got an ipadress that used to be infected in the past. I am sure it is not caused by them to be listed in that list since they have a very secure network. And when I contacted the ISP to get them delisted they told me to use their smtp... They are running Windows server 2003 with Exchange 2003 SP1. Thnx in advance.. Mark