function ckit()
{ // BEGIN FUNCTION DEFINITION
if(document.form.submit_by.value=="")
  {alert("Invalid Email! Please try again..."); return false}
if(document.form.submit_by.value!="")
{
if(document.form.submit_by.value.indexOf("@")==-1 ||
   document.form.submit_by.value.indexOf(".")==-1 ||
   document.form.submit_by.value.indexOf(" ")==1 ||
   document.form.submit_by.value.length<6)
  {alert("Invalid Email! Please try again..."); return false}
}
} // END FUNCTION DEFINITION