It may have changed since then, but Fillipo Valsorda wrote up some details about this, and how to validate how the proxy works - https://blog.filippo.io/how-the

It may have changed since then, but Fillipo Valsorda wrote up some details about this, and how to validate how the proxy works - https://blog.filippo.io/how-the-new-gmail-image-proxy-works-and-what-this-means-for-you/ https://blog.filippo.io/how-the-new-gmail-image-proxy-works-...