function check_mail(cg) {
mail01 = /[^@]+@[A-Za-z0-9_-]+[.]+[A-Za-z]+/;
mail02 = /[^@]+@[A-Za-z0-9_-]+[.]+[A-Za-z0-9_-]+[.]+[A-Za-z]+/;
mail03 = /[^@]+@[A-Za-z0-9_-]+[.]+[A-Za-z0-9_-]+[.]+[A-Za-z0-9_-]+[.]+[A-Za-z]+/;
if(mail01.test(cg.value)) return true;
if(mail02.test(cg.value)) return true;
if(mail03.test(cg.value)) return true;
return false;
}