Code.gs

function TagInbox() {
  // get all threads in inbox
  var threads = GmailApp.getInboxThreads();
  var GlobalLables = GmailApp.getUserLabels();
  // Check if there are the GEOIP label sets in here.
  var HasGeoIP = false;
  for (var i = 0; i < GlobalLables.length; i++) {
    if(GlobalLables[i].getName() === "geoip") {
     HasGeoIP = true; 
    }
  }
  if(!HasGeoIP) {
    GmailApp.createLabel("geoip");
    GlobalLables = GmailApp.getUserLabels();
  }
  
  for (var i = 0; i < 10; i++) {
    // get all messages in a given thread
    var messages = threads[i].getMessages();
    if(threads[i].getLabels().length != 0) {
      var ContainsGeoIP = false;
      var labels = threads[i].getLabels();
      for (var j = 0; j < labels.length; j++) {
        if(labels[j].getName().indexOf("geoip") != -1 ) {
          Logger.log(labels[j].getName())
          ContainsGeoIP = true;
        }
      }
      if(ContainsGeoIP) {
        break;
      }
      if(!ContainsGeoIP) {
        ProcessMsg(messages[0],GlobalLables,threads[i])
      }
    } else {
      ProcessMsg(messages[0],GlobalLables,threads[i])
    }
  }
};

function ProcessMsg(msg,GlobalLables,thread) {
  
  var RawMsg = msg.getRawContent().split("\n");
  // We are looking for
  // Received: from
  for (var j = 0; j < RawMsg.length; j++) {
    if(RawMsg[j].indexOf("Received: from") != -1 && RawMsg[j].indexOf("[") != -1) {
      Logger.log(RawMsg[j])

      var re1='.*?((?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?))(?![\\d])';  // IPv4 IP Address 1
      var p = new RegExp(re1,["i"]);
      var m = p.exec(RawMsg[j]);
      if (m != null) {
        var ipaddress1=m[1];
        var Orign = (GetEmailLocation(ipaddress1))
        var Res = EnsureWeHaveLabel(GlobalLables,Orign);
        GlobalLables = Res[1];
        Label = Res[0];
        if (Orign != "Reserved" && Orign != "Unknown") {
          thread.addLabel(Label);
        }
        break;
      }
    }
  }
}

function GetEmailLocation(IP) {
  try{
    var rawjson = UrlFetchApp.fetch("http://ipinfo.io/" + IP + "/json");
    var obj = JSON.parse(rawjson);
    return obj.country;
  } catch (e) {
    var rawjson = UrlFetchApp.fetch("https://freegeoip.app/json/" + IP);
    var obj = JSON.parse(rawjson);
    return obj.country_code;
  }
}

function EnsureWeHaveLabel(GlobalLables,TargetLabel) {
  for (var i = 0; i < GlobalLables.length; i++) {
    if (GlobalLables[i].getName() === "geoip/" + TargetLabel) {
      return [GlobalLables[i],GlobalLables];
    }
  }
  var NewLabel = GmailApp.createLabel("geoip/" + TargetLabel);
  GlobalLables = GmailApp.getUserLabels();
  return [NewLabel,GlobalLables]
}