RE: Sorbs.net DNS Blacklist

["Dan Denton" <ddenton () PAYLESSOFFICE com>]

My will is broken. I disabled NDR's in Exchange and thankfully the
people at Sorbs saw fit to remove me from their blacklist. Thanks to all
of you who responded to my post. You help is greatly appreciated...

-----Original Message-----
From: John Mason Jr [mailto:john.mason.jr () cox net] 
Sent: Monday, March 13, 2006 11:59 AM
To: Dan Denton
Cc: security-basics () securityfocus com
Subject: Re: Sorbs.net DNS Blacklist


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.

The "proper" way to deal with this is to reject during the smtp 
conversation, that way your mailserver will not generate the bounce 
message and get stuck in a blacklist.

<http://spamlinks.net/prevent-secure-backscatter.htm>

> 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.


Backscatter is bad, I hope you can find a way to fix your problem The
link explains it better than I can


> 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.

It is not about getting the NDR but which server should generate it.



John

<snip>


---------------------------------------------------------------------------
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
---------------------------------------------------------------------------