I have not received any email since Nov 28th. We should be getting 6-8 emails daily. Why??

How are you checking your email?

Have you tried sending yourself a test email?

I sent myself an email (from another email system) and did not see the mail that I sent.

I am checking via Thunderbird (my usual way).  I am also checking via the internet.

I'd suggest next logging into your webmail account at http://webmail.cox.net and see what messages are showing there.  If you're not seeing any messages there go to Settings and check your message filters/rules, allow/block senders, as well as any auto-forward settings that are configured.

Good advice from Chris. 

If that doesn't work, try changing your password and only updating on the one Thunderbird client. That will take care of the possibility of something else downloading the mail before it can be sent to your computer.