filter-header.js

function filterByHeader(search, hdr_regex, labelname) {
  var label = GmailApp.getUserLabelByName(labelname);
  var cnt   = 0;
  
  var threads = GmailApp.search(search);
  
  for (var j=0; j<threads.length; j++) {
    thd  = threads[j];
    msgs = thd.getMessages();
    
    for (var i=0; i< msgs.length; i++) {
      var m = msgs[i];
      var raw = m.getRawContent();
      var headers = raw.substring(0, raw.indexOf("\r\n\r\n"));
      if (headers.search(hdr_regex) >= 0) {
        cnt++;
        thd.markUnimportant();
        thd.markRead();
        thd.moveToArchive();
        thd.addLabel(label);
      }
    }
  }
  
  return cnt;
}

function hasParameter(e, key, def_value) {
  if (e.parameter[key] && typeof(e.parameter[key]) == "string") {
    return e.parameter[key];
  } else{ 
    return def_value;
  }
}

function doGet(e) {
  var search    = "is:unread label:inbox newer_than:1d";
  var hdr_regex = /^X-Trigger:/m;
  var labelname = "kris-test";
  
  return filterByHeader(search, hdr_regex, labelname);
}