function check_fields_complete(){

      var flag = true; //return value

      var email_er = document.getElementById('email_error');
      email_er.style.display="none";

      if(!checkMail()){
          email_er.style.display="inline";
          flag = false;
      }

      return flag;
}
function checkMail()
{
        var x = document.getElementById('email').value;
//      var filter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
        var filter  = /^([\w-]+(?:\.[\w-]+)*)@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$/i
        if (filter.test(x)) return true;
        else return false;

}