Between November 2013–January 2014, Google rolled out a series of updates to the way Gmail loads images in email. These updates affect the way Email Analytics detects and measures opens.
- In November 2013, Gmail started to cache images for emails opened in a web browser or a Gmail mobile app.
- In January 2014, Gmail began automatically downloading images for emails viewed in a web browser and Gmail mobile apps.
These updates can be confusing and hard to explain—this article makes an attempt to clear things up!
The impact of image caching and automatic image downloads
When Gmail automatically downloads and caches images, those cached images—including open tracker pixels, like the ones used with Email Analytics—are stored on Gmail’s servers. Gmail then loads the same images from the same servers for everyone—regardless of whether they open using Gmail in a web browser or a Gmail Android or iPhone/iPad app.
This means that an email opened in Gmail with a web browser will be indistinguishable from an email opened in a Gmail mobile app.
Individual level tracking
Image caching in Gmail means that it is crucial to use individual tracking with Email Analytics in order to properly record analytics. To use individual tracking, you'll need to enter your Email Service Provider's merge tag while setting up your tracking code.
Without individual tracking, Gmail will cache the image/pixel in your tracking code along with all the other images in your email, and serve the same tracking image for all recipients of your email. This means that only the first open using that tracking code will be recorded and you’ll see very few opens for Gmail. Using a merge tag in your tracking code allows us to properly track email opens, even when Gmail is caching images.
How does this change my stats?
While automatic image downloads mean more accurate open rates and a better subscriber experience, it also means some changes to the data available for Gmail opens.
Device and browser detection
Image caching eliminates the ability to determine a Gmail user's specific device or web browser. To be clear, this only affects opens that occur in Gmail, either in a web browser or in a Gmail mobile app. For instance, device tracking will work for an email sent to a @gmail.com address that is opened in Apple Mail, Outlook, the mail client on iOS, etc.
Device tracking will not work for emails opened in the gmail.com interface in a web browser, or using an official Gmail mobile app. In other words, device tracking still works in the places where Gmail is not caching images.
Gmail opens made in a web browser or in a Gmail mobile app are now reported as “Via Gmail's Image Cache.” You'll see this designation for all opens occurring in Gmail products—for both webmail and mobile opens. Emails opened in the native email client on iOS and Android are unaffected.
The table below explains how various types of Gmail opens will be reported by Email Analytics:
|Type of Gmail open||Reports as||Reading environment|
|Gmail in a web browser||Via Gmail's Image Cache*||Webmail|
|Gmail mobile app (Android)||Via Gmail's Image Cache*||Webmail|
|Gmail mobile app (iOS)||Via Gmail's Image Cache*||Webmail|
|Gmail in a desktop client (sent to @gmail address; opened in Outlook, Apple Mail, etc.)||The email client (Outlook, Apple Mail, etc.)||Desktop|
|Email app on Android (sent to @gmail address)||Google Android||Mobile|
|Email app on iOS (sent to @gmail address)||Apple iPhone||Mobile|
*Note that CSV downloads will display this as “Gmail using Google Cache”.
Gmail open rates
Now that Gmail automatically enables images, it's likely that you will see increased open rates for Gmail.
Android open rates
You may see a decrease in Android open rates, especially after January 2014. Before image caching, opens in the native email app for Android and the Gmail app for Android looked the same. After image caching, Android Gmail app opens are lumped together with Gmail web opens and iOS Gmail app opens. In other words, a portion of Android opens have migrated to the Gmail category. Emails opened in the native email client on Android are still reported as Google Android opens.
Mobile and webmail open rate trends
Measuring mobile opens for Gmail is a bit more difficult now, since it's not possible to differentiate Gmail opens with a web browser from opens in Gmail mobile apps. Prior to image caching, Gmail Android and iOS app opens were reported as mobile opens, but with image caching in place, Gmail Android and iOS app opens are reported as webmail opens. Image caching results in ALL Gmail opens looking the same—including Gmail Android app ops.This may make your mobile open rates appear to decrease and your webmail open rates appear to increase.
Forward and print tracking
Forward and print tracking is no longer supported for Gmail opens.
Since the open tracker pixels used to relay information about Gmail opens are now cached on Google servers, you will see the location of Gmail proxy servers or none at all.