Ever wonder why most e-mail clients hide images by default? The reason for the “display images” button is because images in an e-mail must be loaded from a third-party server. For promotional e-mails and spam, usually this server is operated by the entity that sent the e-mail. So when you load these images, you aren’t just receiving an image—you’re also sending a ton of data about yourself to the e-mail marketer.
… But Google has just announced a move that will shut most of these tactics down: it will cache all images for Gmail users. Embedded images will now be saved by Google, and the e-mail content will be modified to display those images from Google’s cache, instead of from a third-party server.
… While this means improved privacy from e-mail marketers, Google will now be digging deeper than ever into your e-mails and literally modifying the contents. If you were worried about e-mail scanning, this may take things a step further.
… There’s also a bonus side effect for Google: e-mail marketing is advertising. Google exists because of advertising dollars, but they don’t do e-mail marketing. They’ve just made a competitive form of advertising much less appealing and informative to advertisers. No doubt Google hopes this move pushes marketers to spend less on e-mail and more on Adsense.