Problems with Open Tracking in Gmail, after changing its image caching.

Problems with Open Tracking in Gmail, after changing its image caching.

At the end of the previous week Gmail made some changes in its image caching that affect how most ESPs count the Open Rate. A few months ago, we analyzed the problems in Email Opens with the new Gmail tabbed Inbox. It seems that campaign reporting with Gmail users is a mysterious task. So is it a war after all?

In order to give you a precise Open Tracking we embed a pixel in an image inside your newsletter. Every time an email is opened, Gmail makes a request for an image, and that’s how we know that the newsletter is being read. But now links to images in emails to Gmail are being replaced with URLs to Google’s own content serving network. It saves image files from unique URLs temporarily and replaces all image URLs in the email content by a call to Google’s content caching service googleusercontent.com. The user’s browser then loads and displays Gmail’s cloned images. When the tracking pixel is cached, another open from one tracking URL hits the cache, not the tracking server of our mailing software. Gmail is proxying requests for images and in doing so is Proxying their requests and thereby masking the original IP address.

In other words, in the new Google setup, the first time an image is opened, Google downloads the image from the image server and caches it on a Google managed proxy. This means that the first image load may be tracked by the sender, but any subsequent image load may not be tracked. This has led many Email Service providers to provide a decreasing number of total opens or in some cases to count unique opens only in their campaign reporting, and created a problem on geo-location reporting.

When we realized the issue at the end of the previous week with our clients’ campaigns, we immediately tested our infrastructure, to prevent this from happening, and to be able to provide accurate Open tracking. After testing and completing some changes, we are happy to say that Moosend’s email campaigns are not affected by these changes from Gmail.

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