Overview
SEM Backscatter was operated by Spam Eating Monkey and specifically tracked sources of backscatter β a form of indirect spam where mail servers generate Non-Delivery Reports (NDRs) or bounce messages in response to forged sender addresses, inadvertently forwarding spam to the victims whose addresses were forged.
Backscatter is particularly harmful because it originates from otherwise legitimate mail servers and is difficult to filter. The SEM Backscatter list allowed administrators to identify and block these servers. Spam Eating Monkey has discontinued its DNSBL services.
How It Works
Spam Eating Monkey monitored NDR flows using trap addresses. When a trap address received a bounce or NDR that it never sent an original email to generate, the originating mail server was flagged as generating backscatter. Servers misconfigured to accept-then-bounce rather than reject-at-SMTP-time are the primary source of backscatter.
How to Get Delisted
Spam Eating Monkey's services are no longer active. To prevent backscatter from your own mail server, configure it to reject invalid recipient addresses at the SMTP DATA or RCPT TO stage rather than accepting and then bouncing β this eliminates the need to send NDRs entirely.