function necessary_value_and_mail2(){
      if ((document.forms['otziv'].fio.value=='') || 
          (document.forms['otziv'].email.value=='') ||
          (document.forms['otziv'].code.value=='') || 
          (document.forms['otziv'].sms.value=='') )
      {
        alert("Не заполнены поля!!!"); 
        return false;
      }
      else 
      {
        var regexp=/^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}$/ //regular expression defining an email address
	       if (document.forms['otziv'].email.value.search(regexp)==-1) { //if match failed
	       alert('Введите правильно Ваш e-mail !!!');
	       document.forms['otziv'].email.value='';
	       document.forms['otziv'].email.focus();
	       return false;
	       } else return true;
	    }
    }