Re: [exim] An interesting observation about spam zombies

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Author: Martin A. Brooks
Date:  
To: Marc Perkel
CC: exim-users
Subject: Re: [exim] An interesting observation about spam zombies
Marc Perkel wrote:
> My theort is that spam zombies do DNS caching so as to maximize spam
> output by eliminating dns lookups. Thus zombies retain old information
> far longer than they are supposed to.
>
> So I'm experimenting with a blaclisting trick where I change my fake
> high MX records, wait several hours, and then anything that hits the old
> fake MX records are spam zombies.


Your theory is flawed. Many many large ISPs ignore TTLs and
overagressively cache DNS records.

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