If you are dealing with Cox email not sending on Windows 10, 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.
Your Internet connection may be very slow. Check with the internet connection in the first step.
If the internet connection is good, then check with SMTP settings. You have set up mail client with valid SMTP parameters. Make sure that you give correct provider, URL and SMTP settings.
If you face issue during sending and receiving webmail, then the problem is with SMTP settings.
Maybe you not given valid credentials for your login details. That shows you the pop message “The username or password for ‘Cox’ is incorrect.”
Some problem arises with SMTP server connection. Confirm that.
Most normally for sending mail port 25 is used.
Sometimes the antivirus or firewall settings may not allow loading Cox webmail.