Subject: [Asrg] Forwarding in the face of spam

From: Alessandro Vesely <[email-masked]>
Date: Fri, 08 Aug 2008 10:22:12 +0200

Hi all,
my apologies for cross posting, but my first question is which list, 
if any, is appropriate for discussing this topic.

Apparently, it is a common practice to gather lists of IP addresses 
for the purpose of dropping, rejecting and/or tarpitting mail requests 
therefrom. (Rejecting and tarpitting can be played at both the TCP/IP 
and SMTP levels.) As a postmaster, I wonder how should I act for, say, 
forwarding all mail destined to a given address on my server to a 
given remote mailbox. IMHO, I should operate the same boundary checks 
as the target server, because it is more annoying and less reliable to 
do DNSBL checking on someone else's "Received" headers. However, 
unless the remote postmasters and I manually arrange some ad-hoc 
procedures, I have no way to know what boundary checks their host 
currently carries out, let alone reassuring them that my server does 
those same checks before forwarding mail to their host.

DNSBL, SPF, and spam reporting are more or less standardized. 
Therefore, designing a mechanism to fix forwarding seems now possible.

As my first question can be answered implicitly, I put some more:

Independently of how a list of IP addresses is gathered, is there any 
reason not to publish it?

Is there any reason why postmasters would not want to say what DNSBLs 
their servers look up and what decisions they make thereafter? If I 
knew my message were to be rejected, I would abort sending tout-court, 
irrespective of my hat's color. Would that be a disadvantage for the 
target host?

TIA for any elucidation
Ale
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From: Ian Eiloart <[email-masked]>
Date: Fri, 08 Aug 2008 10:00:48 +0100

--On 8 August 2008 10:22:12 +0200 Alessandro Vesely <[email-masked]> wrote:

> their servers look up and what decisions they make thereafter? If I knew
> my message were to be rejected, I would abort sending tout-court,

Publishing the list of RBLs that I use would allow spammers to target my 
servers more effectively, and more efficiently. Each spambot that they 
controlled could look up my list, and determine whether they could reach 
me. Spambots can now simply target their mail at servers that are likely to 
accept it.

-- 
Ian Eiloart
IT Services, University of Sussex
x3148
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From: "David Nicol" <[email-masked]>
Date: Fri, 8 Aug 2008 08:08:17 -0500

On Fri, Aug 8, 2008 at 3:22 AM, Alessandro Vesely <[email-masked]> wrote:
> DNSBL, SPF, and spam reporting are more or less standardized. Therefore,
> designing a mechanism to fix forwarding seems now possible.

This is one potential application of "tagging"

The complexity of standardized tagging is in preventing forgery,
public-key encryption seems like the best way to do this

Designing a mechanism is possible, yes, but driving adoption of it is
another sack of camels entirely.

-- 
"don't let the perfect become the enemy of the good" -- some politician on CNN
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