I am somewhat of a novice with exchange, but my question pertains to getting excessive NDRs. It appears that someone is spoofing us, and a bunch of NDR messages are now showing up in our user's mailboxes. Our current environment consists of an internal (not in DMZ)exchange 2003 FE server which is also our bridgehead server. The back-end consists of a exchange 2000 2-node active/passive cluster. I've read in a few articles about reciept filtering and SenderID, and also about turning off NDR all together. What is the best and most secure approach to nullifying all these NDR messages my users are now getting??? Both now and in the future???

Hi, If someone on the internet is spoofing your users e-mail addresses and send a lot of mails using these spoofed addresses there is nothing you can do to prevent the NDR's from entering your system. Leif

Are there any measures I can take now to thwart this type of activity in the future???