App script auto forward email

auto-forward.js

function myFunction() {  
  Logger.log("start")
  var labels=GmailApp.getUserLabels()
  labels[0].getName()
  var forwardedLabel=GmailApp.getUserLabelByName("forwarded")
  for(var i =0 ;i<labels.length;i++){
    var name=labels[i].getName()        
    if (name.match(/fwd:/)) {
      Logger.log("label:" + name)   
      var to=name.match(/fwd:(.*)/)[1]
      Logger.log(to)   
      var threads=GmailApp.search("label:" + name + " -label:forwarded")
      Logger.log("found " + threads.length + " threads" )
      for(var k=0;k<threads.length;k++){        
        Logger.log("doing thread " + k )
        var messages=threads[k].getMessages()
        for(var j=0;j<messages.length;j++){
          Logger.log("forwarding " + j )
          messages[j].forward(to)
        }
        Logger.log("adding label" )
        threads[k].addLabel(forwardedLabel)
      }
    }
  }
  Logger.log("done" )
}