Spam and Backscatter Weighting

Send spam — Get Listed.

Backscatter listings are automatically evaluated before the IP address is listed. The algorithm includes volume, frequency, prior removals and other factors.

In addition to unsolicited bulk email, the following are identified as spam:

1. Challenge/Response challenges.
2. Bounces with a return path other than null (“<>”). RFC 2821 (3.7) states: “When such a message is transmitted the reverse-path MUST be set to null.”
3. Bounces resulting from content inspection. This issue occurs most frequently when server administrators mis-configure filtering software like Symnatec Email Security. Spam must be rejected — NEVER bounced.

References:
Our definition of spam.
More information on backscatter.