Feature: backscatter ruleset

• “backscatter” = bounces, in response to spam sent using a fake address at your domain

• you had nothing to do with it, but the remote MTA still sends you:

• • "user unknown" bounces
  • "your mail was probably spam!" bounces
  • "your mail had a virus!" bounces
  • challenge/response challenges

• volume can be as high as spam itself :(