var ok;
function checkEpostAdresse(field) {
  // the following expression must be all on one line...
  var okEpost = field.value.match(/\b(^(\S+@).+((\.com)|(\.net)|(\.edu)|(\.mil)|(\.gov)|(\.org)|(\.info)|(\..{2,2}))$)\b/gi);
    if (okEpost) {
      ok = true;
      }
    else {
      alert('E-mail adressen skal være gyldig');
      field.focus();
      field.select();
      ok = false;
    }
}

u = window.location;
m = "Check denne side jeg har fundet....";
function mailThisUrl() {
  ok = false
  checkEpostAdresse(document.sendEpost.address);
    if (ok) {
      // the following expression must be all on one line...
      window.location = "mailto:"+document.sendEpost.address.value+"?subject="+m+"&body="+document.title+" "+u;
    }
}