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Date: Mon, 02 Sep 2002 19:53:58 -0700
From: "Kevin P. Fleming" <kpfleming@cox.net>
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To: Matt Bernstein <matt@theBachChoir.org.uk>
CC: Matti Aarnio <matti.aarnio@zmailer.org>, linux-kernel@vger.kernel.org
Subject: Re: [ot] Re: Stupid anti-spam testings...
References: <Pine.LNX.4.44.0209030044210.12780-100000@jester.mews>
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Matt Bernstein wrote:
> 
> Anyway I think this kind of paranoia is just silly. It's trivial to forge 
> a valid sender address, so why bother checking anything other than a 
> syntactically valid domain name?
> 

Because, believe it or not, most spammers don't bother. The main server 
that I maintain (_NOT_ where I receive L-K) drops at least 20 messages a 
day at RCPT TO: time using this very check. Considering that's 50% of 
the spam we drop at RCPT TO: time, I'd say it's worth it.

But I do agree, the systems doing the callouts should cache the results 
(I'm an Exim 4.10 user as well).

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