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How Gmail's new image caching feature influences your analytics

Google has recently introduced a number of changes to Gmail, which affect email marketers. One of the most significant changes is the addition of image caching. How exactly does it affect your emails?

How images are used in email

In addition to their visual appeal, images serve a very important purpose in email marketing: they are used to track email opens and engagement. A unique image is included in a campaign and every time the image is downloaded from the server, the tracking software marks that as an ‘email open'. To count opens reliably, software tools need those images to be downloaded every time someone opens an email.

Enter: image caching

When an image is cached, it is downloaded from the original server and stored on a proxy server. Gmail has now started caching images for users accessing Gmail via the webmail interface: meaning images are viewed only once on the original server while successive views will originate from the cached image on Google's proxy servers.
This practice brings a great speed and reliability improvement to users. But it also means that the unique downloads used by tracking software, will no longer occur. Analytic tools will only see the initial download by Google and won't register subsequent opens, regardless how many times a reader opens that email.

The good news: images are now showing 

On the other hand, Google is also bringing positive image-news. Thanks to the new improvements, Gmail will soon display all images automatically across desktop, iOS and Android.  This means images will no longer be suppressed, there will be no more “display images below” links and your emails will look good when they arrive in people's mailboxes!  Plus an important advantage for marketers: every recipient who opens your email will be tracked from now on

What does this mean for your email analytics?

In a nutshell, these are the changes Gmail's new caching method will bring to e-marketers' reports, engagement and interaction rates.
•    Gmail may track fewer opens.
•    Forward and print tracking won't work via Gmail due to image caching.
•    While open rates may drop, unique open rates may soon start to climb.


Gmail's new caching method will change the way you analyse your open rates. But keep in mind that it also adds download speed and beauty to your emails.

Read more on the subject here!

Posted on
Dec 19, 2013