Build a Gmail Open Tracker with Google Apps Script (GAS)

Concept

How it Works

Gmail's built-in read receipts are only available for Workspace accounts. In this lab, we'll build a custom tracking pixel that works for any Gmail account using Google Apps Script.

Tracking Pixel: A tiny 1x1 transparent image hosted on a GAS Web App.
Logging: When the recipient opens the email, their GAS logs the event.

Step 1 GAS Script

Create a new script at script.google.com and paste this:

function doGet(e) {
  var id = e.parameter.id;
  var sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
  sheet.appendRow([new Date(), id, e.parameter.user_agent]);

  var clearGif = "R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7";
  return ContentService.createTextOutput("")
    .setMimeType(ContentService.MimeType.TEXT)
    .append(Utilities.base64Decode(clearGif));
}

Deployment

Deploy as a Web App and set access to "Anyone".

Step 2 Usage

Embed the tracking URL in your email's HTML:

<img src="YOUR_WEB_APP_URL?id=RecipientName" width="1" height="1">

How it Works

Step 1 GAS Script

Deployment

Step 2 Usage

Download Full Automation Pack