@Override
    public Object getValueAt(int rowIndex, int columnIndex) {
        ClientMail mail = clients.get(rowIndex);
        switch (columnIndex) {
            case 0:
                return mail.getNom();
            case 1:
                return mail.getPrenom();
            case 2:
                return mail.getEmail();
            case 3:
                return mail.getContenu();
            case 4: 
                return mail.getIdMessage();
            default:
                return 0;
        }
    }