function mergeEmail (mailuser,mprovider) { 
  // ergibt den String "mailto:<user>@<domain>"
  // den Link setzen: <a href="javascript:;" onclick="mergeEmail('<mailuser>','<mprovider>')">
  var mtotal='mailto:' + mailuser + String.fromCharCode(64) + mprovider;
  document.location.href = mtotal;
}