In late 2013, Google began to cache all images in email sent to Gmail users, storing remotely-hosted images on their own servers instead of accessing them each time an email is opened. Laura at Word to the Wise wrote up some good info at the time, focusing mainly on the parts of email tracking that were (or were not) affected by the changes.
Fast forward to 2018, and it looks like Yahoo has adopted a similar policy of image caching. According to Litmus, Yahoo recently began caching images on their servers in the same manner as Google. And like Google’s version, this one won’t break open tracking – but could cause some unusual data points or issues with geolocation or user agent tracking. If you track the location of email opens, you’re likely to start seeing a lot more traffic from Sunnyvale, CA (the location of Yahoo’s servers), and any dynamically-generated content based on the location of the recipient will reflect that. In fairness, IP geolocation has never been a precise science, so most marketers should rely on other signals along with that data to serve up location-specific content.
When Google introduced this feature, they used it as a platform to allow images to load by default for all mail sent to the Inbox. There has been no announcement or indication thus far, but is it possible Yahoo is planning a similar feature? As with most of the changes taking place under the new Oath umbrella; we’ll just have to wait and see.