/**
  * Takes the message and adds a header to it.
  *
  * @param mail the mail being processed
  * @throws MessagingException if an error arises during message processing
  */
 public void service(Mail mail) {
   try {
     MimeMessage message = mail.getMessage();
     Classifier classifier = new Classifier(message);
     String classification = classifier.getClassification();
     // if ( !classification.equals("Normal") ) {
     message.setHeader(headerName, classification);
     message.saveChanges();
     // }
   } catch (javax.mail.MessagingException me) {
     log("Error classifying message: " + me.getMessage());
   }
 }