If you're having issues with sending an email to a particular individual, or an email isn't coming through as expected, cPanel will give you the option to look at the mail logs.

1. Login to cPanel.
2. Go to Email Trace.
3. Enter the email address you are sending to or receiving from.
4. Click Run Report.
5. It will then list any logs of emails relating to that email address.

This should give hints as to whether there are any email delivery issues occurring.