Ho appena risolto il problema, Grazie comunque per la risposta

Posto il codice per chi ne avesse bisogno:

Codice PHP:

require('fpdf.php');
require('class.phpmailer.php');
include("class.smtp.php");

class PHPMailerPersonale extends PHPMailer{    
            var $From = "name@yourdomain.com";    
            var $FromName = "Nome";    
            var $Subject = "Resoconto ordine";    
            function SendConControllo (){    
                    if(PHPMailer::Send()){    
                           echo 'mail inviato correttamente'; 
                    }else{ 
                           echo 'mail non inviato a causa del seguente errore: ' . PHPMailer::ErrorInfo;            
                    }        
            }
}
$pdf = new PDF();

// Codice creazione pdf

$doc = $pdf->Output('', 'S');

$mail= new PHPMailer();$mail->IsSMTP();           // telling the class to use SMTP
$mail->Host= "mail.dominio.com";                     // SMTP server
$mail->SMTPDebug =2;                                    // enables SMTP debug information (for testing)
// 1 = errors and messages
// 2 = messages only
$mail->SMTPAuth= true;                                  // enable SMTP authentication
$mail->Host= "mail.dominio.com";                    // sets the SMTP server
$mail->Port= 26;                                            // set the SMTP port for the GMAIL server
$mail->Username= "username";                       // SMTP account username
$mail->Password= "password";                               // SMTP account password

$address = "name@yourdomain.com"; 
$mail->AddAddress($address);
$mail->Body = 'Apri il file in allegato';

// definizione dell'allegato 
$mail->AddStringAttachment($doc, 'doc.pdf', 'base64', 'application/pdf');

// spedizione
$mail->Send();