$(document).ready(function(){
  $("#contact-advertiser").submit(function() {
    var t = false;
    var m = false;
    var filter = /^([\w-]+(?:\.[\w-]+)*)@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$/i;
    if ($("#tel").val() != "") { t = true; }
    if ($("#email").val() != "" && filter.test($("#email").val())) { m = true; }
    if (t || m) {
      return true;
    }
    alert("Please include an e-mail address or phone number (or both if you wish) so the accommodation owner can reply to your enquiry.");
    return false;
  });
});