// Validate email address
  function isValidEmail(str) {
    // are regular expressions supported?
    var supported = 0;
    if (window.RegExp) {
      var tempStr = "a";
      var tempReg = new RegExp(tempStr);
      if (tempReg.test(tempStr)) supported = 1;
    }

    if (!supported) 
      return (str.indexOf(".") > 2) && (str.indexOf("@") > 0);

    var r1 = new RegExp("(@.*@)|(\\.\\.)|(@\\.)|(^\\.)");
    var r2 = new RegExp("^.+\\@(\\[?)[a-zA-Z0-9\\-\\.]+\\.([a-zA-Z]{2,3}|[0-9]{1,3})(\\]?)$");
    
    //validate domain part of the email against all known TLDs as of May 2001 
    var r3 = /\.(a[c-gil-oq-uwz]|b[a-bd-jm-or-tvwyz]|c[acdf-ik-orsuvx-z]|d[ejkmoz]|e[ceghr-u]|f[i-kmorx]|g[abd-ilmnp-uwy]|h[kmnrtu]|i[delm-oq-t]|j[emop]|k[eg-imnprwyz]|l[a-cikr-vy]|m[acdghk-z]|n[ace-giloprtuz]|om|p[ae-hk-nrtwy]|qa|r[eouw]|s[a-eg-ort-vyz]|t[cdf-hjkm-prtvwz]|u[agkmsyz]|v[aceginu]|w[fs]|y[etu]|z[admrw]|com|edu|net|org|mil|gov|biz|pro|aero|coop|info|name|museum)$/i;

    return (!r1.test(str) && r2.test(str) && r3.test(str));
  }