Chatting with Cox about this problem was useless, as is most of their first tier chat and phone support. It finally dawned on me to try filtering.
Like Daryl12, I was seeing a lot of those similar spam messages coming through, just starting over the last few months. I looked at the "to" field and saw that none of these messages actually had my email address in them. So, I set up the following filter.
Go to Webmail > Settings > Message Filters > New Filter
Filter Name: Spam
Filter: For incoming messages where all of the following match: To does not contain youremail@cox.net
Action: Place Messages in: Spam (folder should already be available in pull-down menu)
Ok
This filter will send any email you receive that does not have your email address in the "to" field directly to the spam folder. I recommend you just periodically glance through your spam folder to make sure you're not missing any important messages. Otherwise, this should work.
Obviously, Cox's "spam partners" should be easily detecting these messages as spam, and, obviously, reporting these to cox as spam is not doing a bit of good. Hopefully this workaround will alleviate the issue.