function validEmail(who) {
  var email=/^[A-Za-z0-9]+([_\.-][A-Za-z0-9]+)*@[A-Za-z0-9]+([_\.-][A-Za-z0-9]+)*\.([A-Za-z]){2,6}$/i;
  return(email.test(who));
}

function validateForm(frm) {
  var error ="";
  if (!frm.firstname.value) {
    error = error + " - First Name Is Required\n";
  }
  if (!frm.lastname.value) {
    error = error + " - Last Name Is Required\n";
  }
  if (!validEmail(frm.email.value)) {
    error = error + " - Valid Email Address Is Required\n";
  }
  
  if (error) {
    alert("The form could not be submitted:\n\n" + error);
    return false;
  }
  else {
    return true;
  }
}