Re: [exim] Caching Spammers to Speed Processing

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Author: Marc Perkel
Date:  
To: Exim Users Mailing List
Subject: Re: [exim] Caching Spammers to Speed Processing


Richard Clayton wrote:

>
>In message <42112CC2.7010105@???>, Marc Perkel <marc@???>
>writes
>
>
>
>>After the first spam to 3 or more people I add the IP address of the
>>host to a list. That list returns DEFER when the host reconnects to send
>>more spam. Every hour - I empty the list. The idea being that just in
>>cast there are non-spammers on that host then they only get delayed an
>>hour rather than rejected.
>>
>>
>
>So if $LARGE_ISP$ has a handful of compromised customers sending spam
>through their "smarthost" you will, in practice, never reply anything
>other than DEFER to any customer of $LARGE_ISP$ -- except for the short
>period every hour when none of the bad email is at the front of the
>backlog queue that $LARGE_ISP$ has waiting to send you
>
>

I'm now thinking more in terms of temporilly blocking the from address
for an hour rather than the ISP. - still experimenting.

>In order to simulate quite how bad this will be, I suggest that you
>assume that $LARGE_ISP$ will typically have about one compromised
>customer per 10,000 users, but they are sending you anything up to
>5,000 times the volume of any individual customer. Given that 1% of
>$LARGE_ISP's customers send you email in any given hour you can now
>calculate how big $LARGE_ISP$ needs to be before you never hear from
>them again...
>
>

Large ISPs usually have mant servers. I doubt delaying one of these for
up to an hour would kill everything. But you raise a good point.

>
>
>>So - anyone have any thoughts on this idea? And interest? So far the
>>code to do this is really simple.
>>
>>
>
>should be simple to skip out then :)
>
>- -- 
>richard                                              Richard Clayton

>
>They that can give up essential liberty to obtain a little temporary
>safety deserve neither liberty nor safety.         Benjamin Franklin

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--
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