function check_email(email_form) {
  var problem = false;//flag variable
  
  //validate name
  if(email_form.name.value=="" ||  email_form.tel.value=="" || email_form.email.value=="" || email_form.enquiry.value=="") {
    alert("Please fill in all the required details marked with an *");
    problem=true;
    }
  
  if(problem) {
  return false;
  }else{
    return true;
  }
}