I've written about Netprospex before. For example, talking about how I think their "opt-out" guidance on email marketing is misguided (and how so many others feel the same way). And then there was Peter Seebach's post questioning their touted "verified!" business lists for sale. And most recently, there was that commenter who asked me what I thought of using Netprospex as part of an email acquisition strategy. (My response: "It's like buying a lottery ticket as part of your retirement savings strategy.)
I feel like it's all been said before, so I won't bother going in to any depth on my opinion of companies such as Netprospex. Instead, I'll just link you to their latest Spamhaus blacklisting. The entry is light on details, so I could but speculate as to what happened. But clearly, the blacklisted IP addresses 38.101.213.238 and 174.122.201.114 are now having significant issues attempting to deliver mail to Yahoo, Hotmail, Gmail, Comcast and many other ISPs. Ouch.
(Update: Two SBL entries, from the looks of it. Click on the IP addresses above to link to each.)