Email Validations in Java Script

<SCRIPT LANGUAGE="JavaScript">

function verify()
  {
     
function validEmail(emailV) {
dotV = emailV.indexOf(".", emailV.length-4);
if (emailV.length < 6) return false;
    if (emailV.indexOf("@") < 1) return false;
    if (emailV.indexOf("@") > (emailV.length-4)) return false;
if (dotV == -1 || dotV > (emailV.length-3)) return false;
for (var i=0; i < emailV.length; i++) {
var tempV = emailV.substring(i, i+1)
if (tempV == " " || tempV == "'" || tempV == '"' || tempV == "," || tempV == ";" || tempV == "`" || tempV == "<" || tempV == ">") {
return false;
}
}
}


 if (document.form1.name.value == "")
          {
         alert("Please Fill Your Name");
 document.form1.name.focus();
     return (false);
          }

 


   else if (document.form1.email.value=="")
 {
 alert('Please Enter Your Email address');
 document.form1.email.focus();
 return (false);
 }
else if (validEmail(document.form1.email.value)==false)
 {
 alert('Please Enter a valid Email address');
 document.form1.email.select();
 return (false);
 }
  else if (document.form1.subject.value=="")
 {
 alert('Please Write Your Subject');
 document.form1.subject.focus();
 return (false);
 }
 else if (document.form1.msg.value=="")
 {
 alert('Please Type Your Messege or Query Here');
 document.form1.msg.focus();
 return (false);

 }
 else
 {
 alert('Are you sure want to Submit ?');
 return (true);
 }    
   }
function set(form)
{
  document.form1.elements[0].focus();
}


</SCRIPT>