function validateForm(){
  var emailreg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
  var name = document.forms["contact-form"]["contact-name"].value;
  var email = document.forms["contact-form"]["contact-email"].value;
  var phone = document.forms["contact-form"]["contact-phone"].value;
  var message = document.forms["contact-form"]["contact-message"].value;

  if(name == '' || email == '' || phone == '' || message == '' ){
    alert('Kindly fill-up all the fields.');
    return false;
  }else if(email != 'N/A' && emailreg.test(email) == false) {
    alert('E-mail address format is invalid.');
    return false;
  }else{
    alert('Your details have been sent. Thank you!');
    return true;
  }
}