Webform Advanced setting

I am created webform for user to enter their Email address for new update.
For this I want validation of field as follows:
If email is already presented into Database he shows error:
Following code I am added into webform Advanced Setting :

Advanced validation code:

foreach ($form_values['submitted'] as $field_id => $value) {
  $component = $node->webformcomponents[$field_id];
  if (strpos($component['name'],"email") !== FALSE && valid_email_address($value)) {
    if ($validUser = user_load(array('mail'=>$value))) {
      form_set_error('',t('The email is already present!'));
    }
  }
}

Advanced Processing code:

$Emails = array();
foreach ($form_values['submitted'] as $field_id => $value) {
  $component = $node->webformcomponents[$field_id];
  if (strpos($component['name'],"email") !== FALSE && valid_email_address($value)) {
    $Emails[] = $value;
  }
  
}
   
$message = "Your message here.";

but after submitting form there is no output.
no error.

Please suggest any changes into code. Or How I can do this?
Thank you in advanced for your help.