I disagree with the previous response. If you use DNS blacklists, you are essentially
daming a certain percentage of connecting email serversas spammers. If you are
comfortable about which emails are being filtered using these blacklists, then
stopping the emails before they get into your system is the most efficient option.
Severing the incomming connection before the spam is even received is not really
"boucing the message". Indeed, YOUR server does not generate the NDR; the connecting
server is. If you believe they are an open relay or they house spammers internally,
screw 'em.
-Chase
Network and Systems Engineer
Bullhorn, Inc.
125 B St.
Boston, MA 02127
p. 617.464.2440 ex 119
m. 617.512.0326
www.bullhornstaffing.com
-----Original Message-----
From:R. Scott Perry [EMAIL PROTECTED]
To: "[EMAIL PROTECTED]" ;
Sent: Apr 6, 2004 05:33:51 PM
Subject: Re: [IMail Forum] Theory behind bouncing spam...
>So, as a general rule, we intend to BOUNCE anything that gets identified
>as spam via the blacklists and the phase filtering.
No, no, no. Please do not.
> Here's the question about the theory:
>
>Spammer sends spam to invaliduser(at)domain.com.
>iMail bounces it back to the sender...
>-- theoretically confirming that invaliduser(at)domain.com is a valid user ---
>Thereby inviting more spam to the invaliduser(at) account...
>
>... which would eventually eat up all the bandwidth in the universe and it
>will start raining frogs.
>
>I've heard that this type of "unintentional confirmation of a valid
>account" is an urban myth - but who knows?
>From what we have seen, that is indeed an urban myth.
However, the main reason *not* to bounce spam is that by doing so *you*
become a spammer! Specifically, about 99% of all spam is sent with a fake
return address. So you simply end up sending the spam to someone else. If
you think it is wrong for someone to send you spam, then bouncing spam is
wrong. It's kind of like putting up a sign on the door of your business
"We have an alarm system -- but the guy two doors down does not."
Worse, it is much harder to detect bounced spam than real spam (since the
bounced spam often comes from a "good" source). If too many people start
intentionally bouncing spam, blacklists will get created to list the
mailservers doing this -- which means that your good mail could start to
get blocked.
-Scott
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