CBL listings broken down by ISP
Chris Lewis of Nortel recently posted a breakdown of CBL listings by ISP in news.admin.net-abuse.email. Here's the top ten of his listing:
375649 chinanet.cn.net 130245 cnc-noc.net 102931 telekom.gov.tr 80936 kornet.net 67721 tpnet.pl 51671 dtag.de 47246 rain.fr 33678 interbusiness.it 33500 hananet.net 28433 hinet.net
The article itself can be found here (Message-ID <email@example.com>), and is worth reading for the full list.
The resulting subthread suggested that US-based ISPs are so low in the listings because many of them have blocks on outgoing port 25 connections from cablemodem and home DSL lines.
I'm a bit surprised by the list; I had no idea China was so bad (note that cnc-noc.net is Chinese), or that Turkey would be in third place. dtag.de (Deutsche Telekom) doesn't surprise me at all, as I have a number of systems that have been slammed by a large and aggressive collection of open proxies in their t-dialin.net and t-ipconnect.de domains.