$(document).ready(function() {
  var example_email = 'webmaster@example.com';
  $('.email-example').val(example_email);

  $('.email-example').focusin(function() { 
    if ($(this).val() == example_email) {
      $(this).val('');
    }
  });
  $('.email-example').focusout(function() {
    if ($(this).val() == '') {
      $(this).val(example_email);
    }
  });
  $('.email-example').parents('form:last').submit(function() { 
    if ($('.email-example').val() == '' || $('.email-example').val() == example_email) {
      alert('Please enter your email before submitting the form.');
      return false;
    }
  });
});