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I think: Gmail started caching the email/images in late 2013 to protect against this. So if the sender is watching, they only see gmail servers pull it once to

I think: Gmail started caching the email/images in late 2013 to protect against this. So if the sender is watching, they only see gmail servers pull it once to their cache. The gmail user only ever sees or gets content from Google's cache. To not "download images" is to stop arbitrary image content when you load an email (for me atleast since I stay inside gmail).

recursive 6y ago
How can they cache tracking pixels? Each one has a distinct URL.
- obmelvin 6y ago
  If I understand your question, the cache GP is referring to is not meant to help across users. Rather, when someone sends you an email the images are pulled into a cache [0]. When you view the email you aren't seeing the resource loaded from the tracking pixel URL, but rather a google cached version. This would mean that the sender wouldn't be able to know about you looking at the email multiple times, etc. [0] I don't actually know if it works that way. Just what I believe the GP is saying. I could maybe see this being done so they can run heuristics on the assets, or something like that.
  - daveslash 6y ago
    I worked for someone back around 2013/14 in which we tried to implement some tracking pixels, and what you described was exactly what we ran into with Gmail recipients. When the e-mail lands in the inbox, Google was retrieving the image from your server, caching it, and then displaying the cached version to the user -- so all you knew was that the email was being delivered to the inbox, but couldn't tell if the email was opened. I don't know if that's how it currently works, but that's what we ran into at the time IIRC.
clankyclanker 6y ago
It doesn’t work that way. That’s how it should work, but that’s not how it does work. It only proxies your request, hiding your IP, not hiding the fact that the email was opened at all. https://blog.filippo.io/how-the-new-gmail-image-proxy-works-and-what-this-means-for-you/ https://blog.filippo.io/how-the-new-gmail-image-proxy-works-...
deleted 6y ago
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recursive 6y ago

How can they cache tracking pixels? Each one has a distinct URL.

obmelvin 6y ago
If I understand your question, the cache GP is referring to is not meant to help across users. Rather, when someone sends you an email the images are pulled into a cache [0]. When you view the email you aren't seeing the resource loaded from the tracking pixel URL, but rather a google cached version. This would mean that the sender wouldn't be able to know about you looking at the email multiple times, etc. [0] I don't actually know if it works that way. Just what I believe the GP is saying. I could maybe see this being done so they can run heuristics on the assets, or something like that.
- daveslash 6y ago
  I worked for someone back around 2013/14 in which we tried to implement some tracking pixels, and what you described was exactly what we ran into with Gmail recipients. When the e-mail lands in the inbox, Google was retrieving the image from your server, caching it, and then displaying the cached version to the user -- so all you knew was that the email was being delivered to the inbox, but couldn't tell if the email was opened. I don't know if that's how it currently works, but that's what we ran into at the time IIRC.

clankyclanker 6y ago

It doesn’t work that way. That’s how it should work, but that’s not how it does work. It only proxies your request, hiding your IP, not hiding the fact that the email was opened at all. https://blog.filippo.io/how-the-new-gmail-image-proxy-works-and-what-this-means-for-you/ https://blog.filippo.io/how-the-new-gmail-image-proxy-works-...

deleted 6y ago

[deleted]