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How Gmail Image Caching Is Affecting Your Email Data

There has been a lot of talk recently about changes that Google has made to Gmail that, while great for their users, can potentially make it difficult for marketers to get email blasts seen and opened by those Gmail users and to receive accurate reporting of email opens.

First, marketers were up in arms about the new gmail tabbed interface.  I think the guys over at MailChimp did a great job showing the significance that change has had on email opens, clicks, and unsubscribes, so I won’t rehash that one here.

More recently, however, Gmail announced that they are now going to be showing images to all recipients by default (instead of hiding them and requiring the reader to click a link if they want to load the images). There has been some discrepancy among bloggers about how this is going to impact the reporting that is delivered to email marketers, so I wanted to take a few minutes to outline how this is going to work and detail why this change is both good and bad.

How it Works

Gmail has traditionally opted not to load images until the recipient clicks a link allowing images to display. It does this in an attempt to block potential spam and malicious viruses that often are sent embedded in images.

Now, Google is going to cache the images on a Google-managed proxy server, and then send copies of the images to the email recipient.  So the image file itself will be loaded via the Google proxy server as opposed to the original image source.  This keeps any code and potentially harmful software from loading within the image, as only the image will be loaded, and it will be the copy on Google’s server instead of the original.

Why it’s Good

This is good for the end users of Gmail because it allows them to automatically view images in their email while avoiding the risk of images with embedded code/software/viruses.  As a Gmail user, I think this is fantastic. You can also opt out of this in the “settings” area of your Gmail account, if you so choose, so nothing is being forced upon you (yet).

Also, since Gmail is showing all images by default, it can actually improve the accuracy of statistics for unique message opens.  Previously, if the user didn’t opt to view images, the tracking pixel (the tiny image used to track when emails are opened) also would not load.  The result was an under-reporting of opens among Gmail users.  Now that all images (including the tracking pixel) are loaded by default, this should not be an issue moving forward and your open statistics should be more accurate.

Why it Doesn’t Change Anything

Google’s caching of the image occurs at the time the email is opened, so you will still know when the user opens the email.  Additionally, Google is still respecting the unique URLs associated with industry-standard tracking pixels, instead of showing the same cached tracking pixel to all users. So tracking the time an email is opened and who actually opened the email will continue to work exactly as it did before for users who had opted to view images.

Also, the most useful statistic – click-throughs – is not affected in any way.  Email marketing software is able to collect that information regardless of what happens with the images.

Why it’s Bad

This process does prevent the tracking of multiple opens by the same recipient.  However, that has not historically been a very useful or accurate statistic.

Another, arguably more important issue, is the geo-location of where your recipients are opening their emails.  Previously, marketers could use this information to segment their list by geographic location. Now, all Gmail recipients could start to look like they’re located wherever the Google server is located, which could mean they will all appear to be in California.  This means that instead of targeting an inferred location based on IP address, it will be more reliable for marketers to actually find out where your recipients are located.  You can do this by including location fields on your forms, particularly with the use of progressive profiling on premium content resources.

Tools such as Litmus, which report which device the emails were opened on, post-send, could also be affected. Google’s change means Gmail won’t allow user-agent strings to decipher which devices the images are served on. This means that marketers will not be able to include code that presents a specific image based on the user’s browser or device.


The overarching takeaway here is that Google is more concerned with its primary customers – email users – than they are with email marketers.  They are going to continue making changes to their product that are good for the end user, without much regard to email marketing.

The other takeaway, however, is that this change should not have a dramatic impact on the reporting of your email opens.  Most average email marketers will not notice any changes to the data they actually use – how many people opened the email, and who did or did not open the email.  While some detailed information such as device and location will not be available, this should not have a dramatic impact on most marketers.

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