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Re: Sorbs.net DNS Blacklist
From: Facekhan <facekhan () gmail com>
Date: Fri, 10 Mar 2006 16:15:59 -0500

I am fairly sure the receiving server does not need to send a bounce message out to the sender, just an smtp error code. I think it is either a error 553 or 550 to the other mail server. It is the originating mail server's job to produce a bounce message for the sender when it receives an error code. Standard or not, I think even that functionality is often recommended to be disabled so that spammers can't use dictionary attacks looking for live addresses and the resulting bounce messages produced are more trouble than they are worth for large email systems.

Never used sorbs, but my experience is that roving black list operators take an extreme stance towards getting off the list although asking for money is a new one on me. You might just try telling them (think of it as social engineering) that you disabled the functionality and see if they will take you off the list. Don't pay them, that is clearly extortion IMHO. If they won't take you off, you might want to contact the other Admin and point out that Sorbs is blocking you for a spurious reason and is shaking you down and they may want to cease using that blocklist or otherwise whitelist you to continue doing business.

Jason

Dan Denton wrote:

I've got some updated info since the original posting. I spoke by email
with a gent at payments () sorbs net, and was told that the reason we were
blacklisted was that a spammer sent a message from a forged username at
a particular domain. The email hit an address at our server that was no
longer in use, and of course a bounce message was sent back saying the
address doesn't exist.
Evidently, this response is considered spam in and of itself by
sorbs.net, and that's what got us on the blacklist. Never mind that we
were the ones who got spammed in the first place, and our mail gateway
was only doing what it was supposed to do. I was told that if we ceased
such "harassment", then we would be removed from the blacklist.
Symantec, who makes our gateway, has it documented on their website that
this feature cannot be disabled, and that such responses are required by
RFC 821. I can see the point. If there's no response to the sender of an
email who accidentally puts a typo in the email address they're sending
to, how the heck would they know if their email reached the correct
party or not? They'd receive no response from a real user, and they'd
probably wonder why they're being ignored. In a business setting, that
behavior could lose you money real quick.

Can anyone please let me know if I'm the one being over-the-top here?
I'd also still like to hear other people's input or experience with
these folks.

-----Original Message-----
From: Dan Denton Sent: Thursday, March 09, 2006 9:31 AM
To: security-basics () securityfocus com
Subject: Sorbs.net DNS Blacklist


Does anyone on the list have any prior experience with the folks at
sorbs.net? For the past few weeks a customer who uses a blacklist
supplied by them has had our emails blocked. Previous to this the
company had no problem getting our emails. People at said company want
to receive our emails and are frustrated that they can't receive them
(important stuff like invoices and statements), but their IT admin says
he has no control over the list itself.
I went to sorbs.net, checked our status using one of their utilities,
and the IP of our mail server shows up on their list. I've even sent in
a request to be removed from the list and have received a ticket number.
In their procedures for delisting, they claim that you must "donate" $50
per email they supposedly received in their spam traps, and the
donations are to be made to 2 charities of their choice. I for one think
this is extortion, regardless of whether the intention is to stop
spammers.

Any background or experience you can share would be appreciated. Thanks
in advance...

Dan Denton

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EARN A MASTER OF SCIENCE IN INFORMATION ASSURANCE - ONLINE
The Norwich University program offers unparalleled Infosec management education and the case study affords you unmatched consulting experience. Tailor your education to your own professional goals with degree customizations including Emergency Management, Business Continuity Planning, Computer Emergency Response Teams, and Digital Investigations.
http://www.msia.norwich.edu/secfocus
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---------------------------------------------------------------------------
EARN A MASTER OF SCIENCE IN INFORMATION ASSURANCE - ONLINE
The Norwich University program offers unparalleled Infosec management education and the case study affords you unmatched consulting experience. Tailor your education to your own professional goals with degree customizations including Emergency Management, Business Continuity Planning, Computer Emergency Response Teams, and Digital Investigations.
http://www.msia.norwich.edu/secfocus
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