[jsnell]

I think what is happening is that Apple Mail prefetches all images when the email is received (over a privacy-preserving proxy). So the Apple Mail users show up as opening every single email, which also artificially boosts their market share.

For most other clients, not only does the user need to open the email but they also need to allow images to be shown for that sender. This will artificially deflate both open rates and market share.

[someweirdperson]

> I think what is happening is that Apple Mail prefetches all images when the email is received (over a privacy-preserving proxy).

How does this privacy-preserving work, where the leak is the specific resource being read?

[zwily]

Doesn’t leak your IP address. It also doesn’t tell the server you opened the email, or when you opened it, because it always fetched them whether you open or not.

Basically all the server learns is that the email address went to an Apple Mail client.