Hello Jnet57,
We'll need to look into your issue with the error you're getting. How long have you been seeing this error and does the error pop up on multiple cox.net emails you have, or only on one? I understand when you're not getting the error, you're seeing 100% capacity even after deleting 200 emails. It sounds like you may have reached the max mail quota and will not get new emails until you delete enough emails to clear up enough space for new ones to start getting into the inbox.
Dustin
Cox Forum Support Moderator