Postini Rolls Out Solution for NDR (Non-Delivery Receipt) Spam

Starting about a month ago, we, along with many of our clients, began receiving extremely high numbers of non-delivery receipt (NDR) email notifications.

Correctly generated, NDRs are a helpful way of being notified of email transmission problems. The NDRs in question however, are being generated by spammers falsifying the "FROM" address of an email. NDRs can be generated for many different reasons. Two valid reasons are:

1) if an email is sent to an address that does not exist

2) if the receiving email server has a system in place to determine if the "FROM" address matches the Internet address that is assigned to that domain

If either of these conditions are met an NDR is generated. When the NDR is generated, it needs an email address to respond to and the only address available is the one in the "FROM" field. An NDR is then sent to the user's address that was "spoofed".

Spammers have used these methods to create large amounts of NDRs which slow down business and deny email service.

While we were able to manually resolve this issue for ourselves and our clients, by tweaking settings within Postini, Postini officially released this Technical Bulletin on May 6, 2008 addressing the issue.