UPDATE 12/3/2010: It appears that the CSMA Blacklist is officially going offline. They have updated their website with these details:

Notice: Due to name server configuration issue, DNS traffic was temporarily rerouted to a server that provided improper results. The problem was resolved, however some lookups may return incorrect information for the next several hours. Please check back later if you are still having problems. NOTE: This list is scheduled to be deactivated and should no longer be used in active production.

My Engineers are currently working on removing that Blacklist from our tool as it is no longer a valid list.

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We have received reports that the RBL (Real Time Blacklists) CSMA has gone down.  My Engineers have completed an investigation and they discovered that the RBL CSMA isn’t dead, but their website is offline at this time. Please view the Google Cache of their website for more details. Our tool is working as it should however it appears that CSMA is having technical difficulties on their end.

MxToolBox is not affiliated with any Blacklists, we just provide a public tool that can be utilized to see if you are on a Blacklist. If you are on a Blacklist, rest assured as we do offer Blacklist Protection! For more information please feel free to visit our website or email us at info@mxtoolbox.com.

For more information on what Blacklists are and how MxToolBox can help, read this blog post. We’re always looking for new Blacklists to add, so if you want to suggest one to us, please send an email to support@mxtoolbox.com.

For information about other Blacklists that have shut down or Blacklists that are having problems, view this forum post.