How to Control Non-Delivery Reports (NDR) in Exchange 2000 or 2003

Spammers will attempt to spam every user on your server, by using a 'dictionary' of common email addresses. Unfortunately for others, your mailserver may send out one NDR notice for EACH such attempt. This is a default Exchange configuration, and there are TWO problems with this setup.

The first problem is the NDR will be delivered into the wrong person's Inbox. Tis is because spammers will 'forge' or fake the 'From:' address when they attempt to spam your server. This triggers Exchange into sending a machine-generated email to that 'From' address, and this alone is a problem on many servers. Additionally, because Exchange will unnecessarily 'quote' or embed the spam message, the spammer successfully used your server as a spam relay point (albeit with a Subject: which indicates failures, which users may still open..).

The second problem with NDRs is a spammer can quickly exhaust your TZO Outbound Mail Relay quota if you send enough of these notices out through OMR.
This could lead to a denial of service attack against your server.

The following is a link to Microsoft Technote Q294757:
How to Control Non-Delivery reports in Exchange 2000 or 2003. It is advised to either disable NDR emails, OR it appears you can disable most NDRs and then choose which users or domains can receive such notices.

Keywords: Exchange, DSN, NDR, blowback, backscatter, joe-job, spam, OMR, quota