function isValidEmail(email) {
  return(/^([^@\s]+)@((?:[\-a-z0-9]+\.)+[a-z]{2,})$/i.test(email));
}

$(function() {
  $('#mailinglist_form').submit(function(e) {
    var email = $('#zsn-zsn').val();
    
    if(! isValidEmail(email)) {
      e.preventDefault();
      
      alert('Please enter a valid email address!');
    }
  });
  
  // Fixes placeholder on older browsers
  
  if(!Modernizr.input.placeholder) {
    $('[placeholder]').focus(function() {
      var input = $(this);
  	  
  	  if (input.val() == input.attr('placeholder')) {
  		  input.val('');
  		  input.removeClass('placeholder');
  	  }
  	}).blur(function() {
  	  var input = $(this);
  	  
  	  if (input.val() == '' || input.val() == input.attr('placeholder')) {
  		  input.addClass('placeholder');
  		  input.val(input.attr('placeholder'));
  	  }
  	}).blur();
  	$('[placeholder]').parents('form').submit(function() {
  	  $(this).find('[placeholder]').each(function() {
  		  var input = $(this);
  		  
  		  if (input.val() == input.attr('placeholder')) {
  		    input.val('');
  		  }
  	  });
  	});
  }
});