Google image caching’s effect on email marketing

2 minute read

I leave Sign-Up.to HQ for a few days (to visit Sign-Up.to Australia) and Google manage to change something else. Check out the video for the quick overview of what you need to know, or read on if you prefer your news in print.

In the last few days, Google have introduced a new feature for their webmail users which caches images in email campaigns. This should improve performance for users, but has some consequences for email marketers.

Tracking email opens relies on loading a unique image into the email when it is opened. The good news is that Google’s change won’t stop us tracking unique opens, which is one of the most important statistics. What it will prevent is tracking multiple opens by the same user if they are using the Gmail web client.

Multiple opens is a much less useful statistic though, so it’s not a major concern.

The other consequence of this change is that location data for users of Gmail’s web client is likely to be inaccurate. Where we don’t have address data stored for a subscriber we fall back to using IP address data from the tracking image to determine their location. Google’s change means that we’ll see one of Google’s IP addresses instead of the users. We’re working on alternative options here, but it should only affect a small proportion of users.

If you’re using a dynamic image service like Moveable Ink, or you like to replace images in your email campaigns after they’ve been sent, this is more concerning for you though. Once an image is cached it won’t update in the viewers email, so the first image they see will be the only one. This effectively kills a few neat tricks for updating content – at least for Gmail web users.

Our testing shows this isn’t affecting emails collected and read using POP or IMAP clients and whether Google will roll this out to their app email clients remains to be seen, so for now this impacts only subscribers using Gmail for the web.