First Apple, Now Gmail? How Prefetching Will Skew Open Data

Google is the latest email service provider to make changes that result in fake open signals.

Well, we knew it would happen. First, we saw enterprise email systems sending back false open signals. Then Apple really upped the ante by rolling out their Mail Privacy Protection to all their users.

Now, Google has joined in.

Gmail’s newly-identified image prefetching is the latest (but probably not the last) improvement to chip away at the reliability of Open data.

To be clear, this is not an issue that will have the same widespread effect as Apple’s MPP. But it will further skew your open data nonetheless.

According to Sparkpost, the prefetching only happens under particular and limited circumstances:

1. A Gmail recipient is logged into and has an active session open to the Gmail app (either web or mobile app).
2. An email is sent to the Gmail recipient while their session is active/open.
3. Gmail prefetches all images immediately before the UI displays the email.
4. This image prefetch is in addition to (and different from) Google Image Cache opens, which occurs when the user opens the email.
The image prefetch only occurs when the user is logged into the Gmail application, comes from a Google IP address, and is requested using the following user-agent string:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/42.0.2311.135 Safari/537.36 Edge/12.246 Mozilla/5.0

So, for instance, if your contact leaves Gmail open in a background tab on their web browser, the Google image prefetching will automatically send back an Open signal for any messages that arrive while that tab is open.

The same will happen if your contact has the Gmail app open on a mobile device when a message arrives.

Sparkpost estimates that between 1% – 6% of open signal data in your contact database will be impacted by Google’s update, depending on how much your audience uses Gmail.

So, while this is not nearly on the same scale as Apple’s Mail Privacy Protection, these false signals build up. Add in fake data from enterprise email systems, and your Open rates could be off by 50% or more.

We don’t expect this to be the last time an email service provider makes changes that interfere with open data.

If your marketing automation platform is still taking Open signals at face value, then you need to upgrade. You need a platform that looks past increasingly unreliable Open data and finds the real, human interactions.

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