Gmail blows up e-mail marketing by caching all images on Google servers
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.
Loading images from these promotional e-mails reveals a lot about you. Marketers get a rough idea of your location via your IP address. They can see the HTTP referrer, meaning the URL of the page that requested the image. With the referral data, marketers can see not only what client you are using (desktop app, Web, mobile, etc.) but also what folder you were viewing the e-mail in.
But Google has just announced a move that will shut most of these tactics down: it will cache all images for Gmail users.
brotherhood of LAN
6:52 am on Dec 13, 2013 (gmt 0)
It's worth noting that the marketer can still see the first "open" by the user, and all images thereafter are cached.
A (temporary?) workaround is sending a content-length:0 HTTP header with the tracking image.
7:37 am on Dec 13, 2013 (gmt 0)
With caching in place, can google see any information they couldn't see before?
12:51 pm on Dec 13, 2013 (gmt 0)
it's not clear from the post whether gmail's proxy image server will respect any cache-related HTTP Response headers, such as Cache-Control and Vary.
brotherhood of LAN
4:35 pm on Dec 13, 2013 (gmt 0)
>can google see any information they couldn't see before
It justifies having a local copy at least but their main implied reason is "improving the user experience".
6:29 pm on Dec 13, 2013 (gmt 0)
Actually it doesn't sound like you'll be able to see even the first open.
"E-mail marketers will no longer be able to get any information from images—they will see a single request from Google, which will then be used to send the image out to all Gmail users."
The problem is that it will be Google requesting the image. So you'll see the headers for the request, but they will just tell you that someone with Gmail opened your email, nothing more. And if the cached version is sent to ALL gmail users, you won't see any subsequent opens at all.
Open stats have always been inaccurate and marketers know to take them with a grain of salt, because they rely on the image download and many users don't download images. So all this really means is that the numbers are now known to be even more inaccurate than they were known to be before.
6:57 pm on Dec 13, 2013 (gmt 0)
At least you can still know which email address loaded the image, unless Google will pre-load all images, whether the email ends up being read or not.
7:19 pm on Dec 13, 2013 (gmt 0)
Wow... why didn't anyone think of this before? If the other big webmail providers follow suit we can return to the days of using images in email and having a reasonable expectation that users will see them.
8:23 pm on Dec 13, 2013 (gmt 0)
IanKelley, you will still have the option of not opening images, so that hasn't changed. all that changed is that IF you display images they will be served through a proxy server.
you can still get around part of the problem by making each image url unique-per-email, so at least you know that gmail requested the image for each addressee. however without details, we don't know whether the imaged is cached by the proxy server in all cases or only when initially requested by a gmail recipient.
8:34 pm on Dec 13, 2013 (gmt 0)
Yes that's true for now but once it's been tested the obvious next step is to start allowing images by default. The only reason not to is spam.
12:50 pm on Dec 14, 2013 (gmt 0)
As I have very little faith in Google's rationale for this move, riddle me this.
One you receive a business related email with a confidential graph, view it, and then delete it; does the graph image forever remain cached on a Google server?
Google's style is that they never 'delete' anything.
3:49 am on Dec 16, 2013 (gmt 0)
google will grow full tail...and bite it.
they will turn into the "walmart" of the internet. Clueless flock... others wonder..WT* ?