[reader_1000]

One interesting thing I noticed with Linkedin emails is that it dynamically fetches unread notification count. For example, if someone views your profile, there will be a notification in the website. If you go to your mail and open an old Linkedin email before you check the notification in the website, you will see a little red 1 on the corner of Linkedin logo. Later, if you go to website, clear notification, and then open the same email, you will see that notification counter is gone. If find it quite interesting that Gmail lets this behaviour.

[have_faith]

>gmail let's this behaviour

I'm assuming the server is just responding with a different image depending on a query param embedded in the image url? (an old technique), what should google do? any remote image url could respond with a new image in an old email it's just rare that it happens.

[reader_1000]

It used to prefetch external images [1]. Another option would be asking whether to download external images. I think one can enable this in settings, default is always display external images.

[1] https://arstechnica.com/information-technology/2013/12/gmail... [2] https://news.ycombinator.com/item?id=6896378

[have_faith]

Yeah I always have all images disabled by default and turn them on on a per email basis if it's absolutely necessary. 90% of emails don't need them or just contain tracking pixels.

[RussianCow]

The image is dynamically generated at request time, so there isn't much Gmail can do, aside from eagerly preloading all images as soon as the email comes in.

[reader_1000]

As far as I remember, Gmail used to prefetch images to prevent senders learning if and when recepient opens an email, but if this behaviour changed, I didn't know that.

[snowwrestler]

All Gmail does (or ever did) is proxy the image file so the server hosting it cannot do reverse IP lookup to collect client metadata like geolocation. The server hosting the image sees a Google IP address request the image, not (for example) your phone’s IP address.

But the image request still happens at the time you open the email. Google does not prefetch the images in unopened emails.

And if the image URL is personalized, it can still be correlated with your email address by the sender to record an open. Google does not try to guess which part of the URL they can dump without breaking the image.