I am confused that you worked in the technical field for 20 years but you didn't include technical data about your issue. I have only been in the field 10 years and I give technical data to waitresses when ordering breakfast. 
AFAIK there are no problems with Cox email. I just sent myself a test email from a Cox email to a Cox email and had no problem. While there are no known issues with sending/recieving in general, there are known issues with Cox adjusting it's spam filters, which has been detecting some emails from other providers as Spam. That gives a very specific CDRBL error as seen in this post.
Return-Path: <xxxxxxx@cox.net>
Received: from fed1rmimpo109.cox.net ([68.230.241.158])
by fed1rmfepo203.cox.net
(InterMail vM.8.01.05.28 201-2260-151-171-20160122) with ESMTP
id <20161117210922.SKDA4109.fed1rmfepo203.cox.net@fed1rmimpo109.cox.net>
for <xxxxxxx@cox.net>; Thu, 17 Nov 2016 16:09:22 -0500
Received: from UserPC ([108.x.x.x])
by fed1rmimpo109.cox.net with cox
id 999A1u00K2zVAzw0199BXQ; Thu, 17 Nov 2016 16:09:11 -0500
X-CT-Class: Clean
X-CT-Score: 0.00
X-CT-RefID: str=0001.0A090201.582E1C77.00C8,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0
X-CT-Spam: 0
X-Authority-Analysis: v=2.1 cv=C+5JsV7+ c=1 sm=1 tr=0
a=l71Q3dNd7MBCNKViW3y/Cg==:117 a=l71Q3dNd7MBCNKViW3y/Cg==:17
a=L9H7d07YOLsA:10 a=9cW_t1CCXrUA:10 a=s5jvgZ67dGcA:10
a=r77TgQKjGQsHNAKrUKIA:9 a=6K60Jccb2wXITVdJksQA:9 a=CjuIK1q_8ugA:10
a=SSmOFEACAAAA:8 a=rmTahHrtcYyws5RCmYMA:9 a=gKO2Hq4RSVkA:10 a=UiCQ7L4-1S4A:10
a=hTZeC7Yk6K0A:10 a=zjWhRoSqWz9hl55Hdlzg:22
X-CM-Score: 0.00
Authentication-Results: cox.net; auth=pass (LOGIN) smtp.auth=xxxxxxx@cox.net
From: "test" <xxxxxx@cox.net>
To: <xxxxxx@cox.net>
Subject: test 1117
Date: Thu, 17 Nov 2016 16:09:10 -0500
MIME-Version: 1.0
Content-Type: multipart/alternative;
boundary="----=_NextPart_000_0000_01D240EC.EF384EB0"
X-Mailer: Microsoft Office Outlook, Build 11.0.5510
Thread-Index: AdJBFtdLAl7maMxHR02TWI+Xdg8d6g==
X-MimeOLE: Produced By Microsoft MimeOLE V6.1.7601.17609
Message-Id: <20161117210922.SKDA4109.fed1rmfepo203.cox.net@fed1rmimpo109.cox.net>
Edited by Trikein, 17 November 2016 - 04:40 PM.