On December 12 Google announced that Gmail will be loading images by default in all new emails. That is great news as it improves user experience and causes emails that have images to look better by default. The way that they are doing it though, is causing a lot of Email Service Providers (ESP) some grief.
"Instead of serving images directly from their original external host servers, Gmail will now serve all images through Google’s own secure proxy servers."
The reason that this causes concern is that just about every ESP uses a 1x1 pixel transparent image to track when an email gets opened. If that image is being loaded from Google's proxy servers then that means that it's only getting loaded from the ESP the first time the email opens and not for subsequent opens.
Here is the good news, though. In our tests we have found that our technique of delivering the tracking image within our Campaigns app is not affected by this change. This means that as long as images are displayed, all opens by a single subscriber will be tracked.
The other bit of good news is that since images are now being displayed by default, more of your emails to Gmail accounts will naturally be tracked and your email statistics should be more accurate.