function lookupEmail(form) {
  var emailAddress = $("input[@name=email]", form).val();
  if (emailAddress != "enter email address" && emailAddress.length > 0) {
    if (cache[emailAddress] == null) {
      jQuery.getJSON(
        "/services/ajax/",
        { method : "authenticate.emailToWebname", email : emailAddress },
        function(json) {
          if (json.stat == "ok") {
            cache[emailAddress] = json.result.webname;
            showFeed(form, json.result.webname);
          } else {
            showError(form, "ERROR: Could not find email address");
          }
        }
      );
    } else {
      showFeed(form, cache[emailAddress]);
    }
  } else {
    alert("Please enter your email address.");
  }
}