$(document).ready(function(){
  $('span.email').defuscate();
});

jQuery.fn.defuscate = function() {
  return this.each(function(){
    var email = $(this).html().replace(/\s*<.*>\s*/, "@");
    $(this).before('<a class="dontbreak" href="mailto:' + email + '">' + email + "</a>").remove();
  });
};