If you are dealing with , then check out the steps:
Check the email in other folders with Cox email that includes trash and spam folder.
Check Cox email account filters and see if the new incoming email is not being filtered out.
Ensure that you have not blocked the recipient.
Also, make sure that the sender does not block you.
Check the POP and IMAP settings, and you can’t even send an email if the Cox email SMTP server is not working.
Lastly, disable the antivirus software installed on your device.