blowback, was Spamhaus...

John Levine johnl at
Sun Feb 21 05:38:22 UTC 2010

>For the purpose of the following two paragraphs, pretend for the moment
>that you operate a business selling stuff via an email address
>Sales at Example.Com.  For dramatic effect, assume your children will
>starve if you are not able to sell anything.
>Further, pretend that you have really annoyed somebody--a competitor,
>perhaps.  Suppose that your competitor has contracted with a real,
>genuine spammer to send email mmessages advertizing some trash at a rate
>of tens of thousands per second until the bot-net gets shut down   using
>Sales at Example.Com as the Return-Path.

Lest anyone think this is a hypothetical argument, for a while I had
annoyed some eastern European spammer enough that I was getting
400,000 blowback bounces a day on a server that never sent more than
10,000 outbound messages/day.

I was able to deal with it via some custom patches in my SMTP daemon,
since the blowback had technical characteristics that made it possible
to recognize efficiently, but it wasn't pretty.


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