I need stop sending Non delivery report becose of spam. I did it by the article on MS web http://support.microsoft.com/kb/294757/en-us But it do not work. My server still send NDR's messages. Version of Exchange server is 6.5.7638.1 JNJN

What you really need to be doing is recpient filtering against Active Directory and do not accept messages for invalid recpients. http://support.microsoft.com/kb/823866 Create a recipient filter When you use recipient filtering, you can prevent messages from being delivered to e-mail addresses that exist in your organization, and you can filter messages that are directed to e-mail addresses that do not exist in your organization. Recipient filtering only applies to messages that come from anonymous connections. To create a recipient filter, follow these steps: Start Exchange System Manager.Expand Global Settings, right-click Message Delivery, and then click Properties.Click the Recipient Filtering tab.To filter e-mail based on a particular e-mail address, click Add, type the e-mail address, and then click OK.To filter messages that are directed to e-mail addresses that do not exist in your organization, click to select the Filter recipients who are not in the directory check box