Email Forwarding

I've used email forwarding for years to allow my wife and i to share some of our emails using a common address. Some time in the Nov/Dec time frame, they stopped working. I've reset everything in settings, but still not joy. I tried forwarding to my gmail account, and it works fine. Any idea why forwarding to a cox.net email address no longer works?

Help ticket opened last week. Bumped to tier-2. No response.