Legit emails marked as "spam" by Cox

Hi,  Cox has once again marking some of my legit emails as "spam".  The messages do get delivered to my inbox as I set up email filters to deliver all of the emails to my inbox whether or not they are marked as "spam".  Over the past several months, I have sent several incorrectly "spam" flagged emails (along with the complete header info) to the "ThisIsNotSpam@Cox.net" address but nothing has changed.  I realize that Cox has outsourced their email service, but there should be a method to stop legit emails from being flagged as "spam" by the company that handles Cox's email service.  There used to be a "this is not spam" feature in Cox's webmail, but that disappeared a while ago.  A search of the Cox email forums shows that this is a long standing problem for Cox's customers, but there doesn't appear to anything Cox or its outside email service is willing to do to correct this problem.