It's been a week and the problem still exists. Just now on 22 March 2018 at about 5:10 PM I replied to an email, while the mail was sent instantly, it took Cox over a minute to respond that the mail had been moved to the sent folder. What this does is prevent me from closing the send window. Some times the response from Cox is quick, usually in the morning hours, but afternoon seems to be a big issue, I am assuming your servers are becoming overloaded and can't respond on demand.
This is just more feedback for an ongoing problem.
Warren McBride