PhpMailer: undisclosed recipients

[ANTAGONIA]

Buon giorno.
Ho il problema di non vedere il destinatario della mail, mi ritorna undisclosed recipients.
Questo è lo script che conoscete bene:

function setUp() {        
global $global_vars;        
global $INCLUDE_DIR;            
global $UTENT_EMAIL;    
global $PRIORITY;        
$this->Mail = new PHPMailer();
$this->Mail->Priority = $PRIORITY;        
$this->Mail->Encoding = "8bit";        
$this->Mail->CharSet = "iso-8859-1";    
$this->Mail->From = "webmaster";    
$this->Mail->FromName = "antonio lubrano";        
$this->Mail->Sender = "";        
$this->Mail->Subject = "Aggiornamento";        
$this->Mail->Body = "";        
$this->Mail->AltBody = "";        
$this->Mail->WordWrap = 0;
$this->Mail->Host = "relay.azienda.it";
$this->Mail->Helo = "";        
$this->Mail->SMTPAuth = false;        
$this->Mail->Username = "";        
$this->Mail->Password = "";        
$this->Mail->PluginDir = $INCLUDE_DIR;    
$this->Mail->ConfirmReadingTo = "webmaster@azienda.it";
if(strlen($this->Mail->Host) > 0)            
$this->Mail->Mailer = "smtp";        
else{            
$this->Mail->Mailer = "mail";        
$this->Mail->Sender = $UTENT_EMAIL;        
}        
global $global_vars;    
$global_vars = array('mail_to' => $UTENT_EMAIL, 'mail_cc' => '','mail_bcc' => '');    
$this->SetAddress($global_vars["mail_to"], $UTENT_EMAIL);
} 

Come risolvo il problema?
Grazie.
Buona giornata.