It appears the new spam filtering service Cox is using (cloudfilter.net) is blocking a lot of valid mail. I would like to know where our individual portals and addressbooks are that we can configure our own whitelists and to be able to see what messages are being rejected. It is one thing to be identify a message as spam, and another thing entirely to reject them without notification. I have mail senders from a good number of places and since my mail volume has dropped by over 75%, it is quite safe to assume the spam aggressiveness thresholds are set quite high as well as are the bulk sender identifiers and anti-spoofing features.
While you claim to not whitelist senders, you do need to provide your users the ability to do so. No doing so means you are censoring email
Also, it is poor form to put a like to review changes and then have it error out.
If you are going to implement such a service you should become a lot more responsive with corrective actions. I am now on my second day waiting for an answer on my ticket with Tier 2, and third day with the actual issue at large.