Of course, but it's a whac-a-mole game. Such instances can be detected (e.g. if you see 100 emails with the same HTML, but with image URLs that are slightly di

Of course, but it's a whac-a-mole game. Such instances can be detected (e.g. if you see 100 emails with the same HTML, but with image URLs that are slightly different). Google can then prefetch those images or it can re-enable the optin for displaying just for those emails. If I were to do email tracking, I would just filter the GMail accounts out of the statistics, because you can't be sure of when GMail's proxy loads those images and what you're interested in is the conversion rate (not in the total number of people that opened their emails, you only care about totals for emails sent and clicks). But a service like MailChimp is not interested in doing this, because MailChimp is a third-party that's interested in showing big numbers to their customers. And putting these numbers aside, the privacy issues related to IP tracking, or the security issues are gone. So I think this is good.