function checkfields(){

if (document.forms["form1"].email.value=="")
        {
                alert("Please enter a valid email address.");
                document.forms["form1"].email.focus();
                return false;
        }
        if (document.forms["form1"].email.value.indexOf("@")==-1)
        {
                alert("Please enter a valid email address.");
                document.forms["form1"].email.focus();
                return false;
        }
        else
        {
           substremail = document.forms["form1"].email.value.split("@")
           if (substremail.length > 1)
           {
              index = substremail[1].indexOf(".")
              if (index == -1)
              {
                 alert("Please enter a valid email address.");
                 document.forms["form1"].email.focus();
                 return false;
              }
          }
          else
          {
             alert("Please enter a valid email address.");
             document.forms["form1"].email.focus();
             return false;
          }
}
}