public function __construct($mailbox)
 {
     parent::__construct('Mailbox ' . $mailbox . ' does not exist');
 }
 public function __construct($messageNumber, $mailbox)
 {
     parent::__construct(sprintf('Message %s cannot be moved to %s', $messageNumber, $mailbox));
 }
 public function __construct($messageNumber)
 {
     parent::__construct(sprintf('Message %s cannot be deleted', $messageNumber));
 }
 public function __construct($user)
 {
     parent::__construct('Authentication failed for user ' . $user);
 }