Awhile back, I discovered that the IP block I was assigned to had been blacklisted for Spamming. This was because someone else (within the same IP block) was repeatedly Spamming and, IMO but I'm only guessing, the NOC didn't do anything about at the time.

The caused all kinds of problems for me and forced me to move to another DC, NOC, and State -- which is much better BTW. :)

At the time though, it came to me that it would be nice to have one place I could go to and check the Major Spam Databases -- rather than one at a time -- to see if current or pending IPs are already listed. Having now found such a place, I thought I would pass it on, with the hope it will help others as well.

Below is the URL to the site, using one of the old IPs I had been assigned. It is an example of what you "don't want to see - that big red line" for any IPs of yours. (Note: the Spam listing was applicable at the time of this posting and may not be red-lined at a future date)

http://www.dnsstuff.com/tools/ip4r.ch?ip=64.83.104.39

http://www.openrbl.org will check the 30 big databases.
Good place to go BEFORE you sign a deal w/ someone. Also check nana-e and -sightings usenet group for that provider.
Last, but not least, get something in the contract that says if the IP block gets listed in "X" number of DNSBL's (we're all somewhere) or in "Y" DNSBL, you don't have to pay for degraded service, unless it was you that got them listed.