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List:       opensuse
Subject:    Re: [opensuse] Can spam be defeated?
From:       Sandy Drobic <suse-linux-e () japantest ! homelinux ! com>
Date:       2006-12-21 10:26:38
Message-ID: 458A615E.2090408 () japantest ! homelinux ! com
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John Andersen wrote:
> On Wednesday 20 December 2006 23:37, Joachim Kieferle wrote:
>> IF BY ACCIDENT a mail is blocked, the positive effect from that is, that
>> the senders are informed about blocking (e.g. Blocked - see
>> http://cbl.abuseat.org/lookup.cgi?ip=82.197.44.218), whereas
>> SpamAssassin "just" marks the spam and one tends to delete the spam
>> without even reading the header / sender.
> 
> Whoa there big fella!
> 
> You are ADDING to the PROBLEM by generating backscatter, and 
> probably joe jobbing some poor schmuck who the spammer 
> pretended to be.  

Wrong. The mail is not accepted and instead REJECTED during the smtp 
dialogue. The responsibility for the mail remains with the sending client. 
May that be the spammer or a normal mailserver.

Dec 17 04:52:12 spamkill postfix/smtpd[18477]: NOQUEUE: reject: RCPT from 
customer.optindirectmail.83.sls-hosting.com[204.14.1.83]: 554 5.7.1 
Service unavailable; Client host [204.14.1.83] blocked using 
zen.spamhaus.org; http://www.spamhaus.org/SBL/sbl.lasso?query=SBL27197;

Opt-in, yeah, sure...

Not even a queue file has been created yet. That is exactly the difference 
to the normal use of amavisd-new or spamassassin: that filtering happens 
after you accepted the mail, so you can't reject the mail at that stage. 
At that point you can only tag-and-deliver.

The biggest problem on the corporate side are gateway mailserver that 
accept a mail without knowing if the recipient is even valid. They try to 
relay the mail to the internal exchange server which is then telling them 
the recipient is invalid. Then they bounce the mail back to the, in case 
of spam forged, sender address. That is the backscatter we all know and 
love. :-((

Sandy


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