I think I assumed 'tracking pixel' was just a metaphor — you mean they're literally serving 1x1 images? Why not 0x0 images? Why not a single transparent pixel?

The pixels are transparent. Gif was the earliest format that supported this.

0x0 pixels arent a valid image, iirc.

All of tracking pixels I've worked with come with a css attribute "hidden", so they don't actually show except in some edge cases.

Huh... I thought browsers didn’t fetch hidden images. Or is that only if the image or its parent elements are "display: none"?

I don't _think_ either case it true.

Because no one thought that the background would change or something like dark-mode would appear ;) 1x1 image was "good enough".

I remember learning ~20 years ago to always set `background-color: #fff` since, in those days of Netscape, a user could easily customise their browser's default background color. It was very useful to have someone on the dev team who was weird enough to have done just that! :)

Well, you still can.. (browser.display.background_color in Firefox)

Sure, but that's why I said "easily" - iirc, it was more an end-user feature than a power-user one.

I use a browser extension on Chrome called PixelBlock to (hopefully) kill those email tracking pixels. The extension displays a small icon on emails where blocking occurred.

This is the description supplied for the extension: "PixelBlock is a Gmail extension that blocks people from tracking when you open their emails."

Yeah, but this is about the Internet as a whole not just Gmail IMHO. You need more than that extension to block it then.

I use Privacy Badger by the EFF. They block all kinds of tracking.

Also using Firefox will prevent Browser fingerprinting and such.

everyone should do this.

On mac turn off: Mail -> Preferences -> Viewing -> Load Remote Content in Messages

Without it, viewing a spam or phishing email will confirm your email address.

Viewing other emails will confirm that you viewed it, when you viewed it, how many times you viewed it, etc.

sigh, what a cesspool.

The "how many times" isn't always true. I work with email a lot at my job and email image caching is getting more aggressive.

I know it's possible to load remote images in emails, but I don't think I've heard of anyone doing so until now.

Wait, so it's a literal pixel?