Spamhaus, widely regarded as the ultimate authority on declaring sources of email as generating spam, has announced a new RBL (define) launching today. This will join the many other RBLs they already currently host which provide large ISPs and email receivers the tools to scrub incoming mail sources for known areas of concern and block at will.
Specifically, the CSS (Composite Snow-Shoe) list will target IPs that appear to have bot-nets associated with them and mail being sent off through rolling IPs and domains to drop bad reputation for the next in line. This allows spammers who’ve infected computers to not risk having their reputation follow them, thus making it harder for the source to be tracked. Until now.
As Spamhaus states:
…this is an automatically-generated list of IPs that have been detected sending snowshoe spam. The CSS contains only single IPs (a/k/a “/32s”), not larger CIDR IP address ranges. CSS listings are automatically removed a few days after the last time a listed IP or one of its near neighboring IPs stops sending snowshoe spam.
You should never find yourself on a Spamhaus list if you are a legitimate emailer. However, issues do arise sometimes where email can find it’s way to a spamtrap and onto Spamhaus. The CSS, though, is one that will be very hard to get on unless multiple data points are accumulated showing a pattern of snow-shoeing. If you do find yourself on this list, it’s time to take a long hard look at the IPs and URLs you provide.
Besides Spamhaus announcing this today at their site, EmailKarma.net also picked it up.
Chris Wheeler
Director of Deliverability, Bronto Software
Last 5 posts by Chris Wheeler
- What the !#$@ do I do with the headers? - April 19th, 2010
- Where the !#$@ are the headers? - March 29th, 2010
- Deliverability Forum: It's a Wrap! - January 11th, 2010
- Cultural Bias: A Discussion Around ISP and ESP Relations - December 17th, 2009
- Future of Deliverability: A Series - November 16th, 2009






This is very good in the fight against botnet abuse and spam. Thanks for letting us know.
~Joseph
I certainly hope they succeed in reducing the amount of spam that is sent out on the Internet with this. However, we found ourselves on their list because of a client they say is snowshoeing ( have not seen the emails yet) and they blacklisted over 16K of IP space. I would sure like them to return my emails to them asking what to do next? I definitely believe RBL lists do a great amount of good reducing spam, I just hope it does not lead to over zealousness.
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You all are sheep. This has NOTHING to do with botnet spam, it only takes out legit mailers. XBL is for their botnets.
CSS SBL is listing valid mailers ranges and no one cares.
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