Re: [exim] Spam filtering of blacklisted name serers

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Author: Tony Finch
Date:  
To: Mike Cardwell
CC: Exim Mailing List
Subject: Re: [exim] Spam filtering of blacklisted name serers
On Wed, 1 Oct 2008, Mike Cardwell wrote:
> Marc Perkel wrote:
> >
> > I'm having luck looking up the name servers of the sending host to see
> > if it's blacklisted
>
> But how accurate is it?


I did some similar experiments, and I found that it's not unusual for an
email-oriented blacklist to catch a nameserver used for legitimate email.
For example, a hosting service that has various dodgy web servers gets a
/24 blocked which happens to include a nameserver which is not just used
for the dodgy webservers but for various other well-behaved customers.

> It seems that any host with valid RDNS of *.pipex.net is in your
> whitelist. Who knows what else lurks in your lists. Any chance of
> publishing the list data?


Funnily enough I seem to remember problems with one of Pipex's name
servers, though I was using a different blacklist. However I can't
remember which company behind the Pipex name it was...

Tony.
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