Google Apps Script to autoforward based on convention.

autoForward.js

/**
 * script to automatically forward all mail under 'auto/forward/[recipient]
 * author: tedsteinmann
 */

//setting primary inputs
var LABEL = 'auto/forward/';

function forwardMail(){
  //get all labels under LABEL
  var forwards = _getAutoForwards()
  //loop over list of labels
  for (var i = 0; i < forwards.length; i++) {
    //Logger.log(forwards[i])
    _forward(forwards[i])
  }
    
}

function _getAutoForwards(){
  var results = [];
  var labels = GmailApp.getUserLabels();
  for (var i = 0; i < labels.length; i++) {
    var labelname = labels[i].getName().toString()
    if(labelname.indexOf(LABEL) > -1) {
      var list = labelname.split("/")
      var forwardTo = list[list.length - 1]
      Logger.log("Checking label: "+ forwardTo);
      results.push(forwardTo)
    }
  }
  return results;
}

function _forward(recipient) {
  var label = LABEL + recipient
  var threads = GmailApp.search('label:' + label);
  for (var i = 0; i < threads.length; i++) {
   var message = threads[i].getMessages()[0]
    message.forward(recipient);  // only the 1st message
    Logger.log('Message subject:' + message.getSubject() + ' forwarded to ' + recipient); //logs MyLabel
    threads[i].removeLabel(GmailApp.getUserLabelByName(label));
  }
}