I received an email from the Time Warner systems administrators this morning in regards to my email not working.
It appears that the IP address of the sender is being blocked by one or more 3rd party blacklist sites. While Time Warner is not affiliated with these sites, we do take their lists into account in order to protect the whole of the Roadrunner users from spam. They will need to contact these sites in order to have the blocks removed. Once this is done, then you should see the errors go away. To find out which sites they are blacklisted on, please go to www.mxtoolbox.com and enter the IP address of 126.96.36.199. This will give you a comprehensive list of who has found the IP address to be questionable. They will need to contact each individual blacklist group to have the IP removed from their listing.
So it appears that Time Warner is blocking email from Canonical due to their using some sort of blacklisting tool which queries this on-line database. When I check the database there are two sites that list Canonical as blocked
Now this is where it gets interesting. I went to those sites and was told by Backscatterer.org that the listing would expire on August 29th unless I wanted to pay $75 for expedited removal. That seems more like blackmail than a legitimate blacklisting process. At this point it looks like I have to continue to change over all my email lists to an email that is not on my ISP and change my business cards. I am not sure what good it will do to tell my ISP that they are blocking a legitimate company due to a policy of blocking email because a domain has two block results in a large list.