linux-kernel - Re: Postgrey experiment at VGER

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Message-ID: <4580A827.7080200@nersc.gov>
Date:	Wed, 13 Dec 2006 17:25:59 -0800
From:	Thomas Davis <tdavis@...sc.gov>
To:	Dumitru Ciobarcianu <Dumitru.Ciobarcianu@...s.ro>
CC:	Matti Aarnio <matti.aarnio@...iler.org>,
	linux-kernel@...r.kernel.org
Subject: Re: Postgrey experiment at VGER

Dumitru Ciobarcianu wrote:
> On Wed, 2006-12-13 at 01:50 +0200, Matti Aarnio wrote:
>> I do already see spammers smart enough to retry addresses from
>> the zombie machine, but that share is now below 10% of all emails.
>> My prediction for next 200 days is that most spammers get the clue,
>> but it gives us perhaps 3 months of less leaked junk.
> 
> IMHO this is only an step in an "arms race".
> What you will do in three months, remove this check because it will
> prove useless since the spammers will also retry ? If yes, why install
> it in the first place ? 
> 
> 

spammers are already re-trying; but they give up after 10 minutes. 
As the delay time increases, the chances of getting on a blacklist 
increase, which makes it easier to identify a machine as a spamming bot.

I normally let my greyfilters run at 30 minutes deny, and 72hrs of 
lease time on a IP/To/From tuplet.  This setting seams to be pretty 
effective in dropping spam; at one point, upto 10k spam vs. a couple 
hundred ham messages.

thomsa
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