This can be used to customize the email headers of feedback emails. By default the email is encoded with UTF8 and HTML is allowed.

/**
 * Replace the email headers of feedback emails. 
 *
 * @param array $headers default body.
 * @link https://developer.wordpress.org/reference/functions/wp_mail/
 * @return string
 */
function custom_function( $headers ) {
  $headers[] = 'Cc: John Doe <name@email.com>';
  return $headers;
}

add_filter( 'helpful_feedback_email_headers', 'custom_function' );