I have an interesting problem and can't seem to find a solution. If anyone in my network sends an e-mail to non valid address they do not get an NDR in return. I checked my SPAM filters and see that they are getting blocked because they are coming in from a blank sender. This also happens if someone from the outside sends an e-mail to an invalid address on my network. Our NDR gets sent from the Exchange server but our backend SPAM filter (Surf Control)blocks it from going out because the sender is blank. How do you change the NDR so it comes from someone, like postmaster or System Administrator? We are using Exch 2K3 w/SP2. Keep in mind that I tried creating a domain account named postmaster and delegated it full control in exchange. Any help would be appreciated. thanks.