Backscatter & challenge response

[Paul Houselander (SME)]

Hi

In common with lots of people I've seen a massive increase in the amount of
backscatter my domains are getting. I implemented watermarking which has
helped a great deal.

What I'm getting complaints about now are the mails coming in from annoying
challenge response systems, the mails don't come from postmaster, <> etc...
so the watermark does not get looked at.

Just wondered if anyone had any bright ideals as to how to combat it?

I've been looking at a selection I've been sent through this morning and
there doesn't seem to be anything consistent about them and there not
hitting many spamassasin rules.

Cheers

Paul