function checkform(form) {

  if (form.namefield.value == "") {
    alert( "Please enter a name." );
    form.namefield.focus();
    return false ;
  }
  
  if (form.emailfield.value == "" || form.emailfield.value.indexOf ('@', 0) == -1 || form.emailfield.value.indexOf('.', 0) == -1) {
     alert( "Please enter a valid email address." );
    form.emailfield.focus();
    return false ;
  }
  
  return true
}