Also it's generally useful to know if a particular email is read so you can test out different formats and whatnot.
Probably because those email newsletters are spam sent to people who interacted with a form once.
That's because you're spamming them.
> even if they signed up for the emails in the first place
Users can change their mind. Clicking anything in an email leads to susceptibility of phishing. So they shouldn't need to click an unsubscribe link to do so. Reporting you for spam is the safest option from their perspective.
And I would argue that most users didn't sign up for the emails. They were conned into giving their email and usually for a completely different purpose.
> Also it's generally useful to know if a particular email is read so you can test out different formats and whatnot.
That's a very dubious assertion. Formats are in the content of the email. Different formats won't tell you why one email was opened while another was not.
Formats can include different titles and descriptions, which can make a huge difference in how often users open your emails. Also just different kinds of emails you might want to send (maybe you send some users an email with a coupon, and some with a new product notification).
Maybe you don't see the value in having people know whether you read their email, which is fine, but there are clearly tonnes of legitimate use cases for having that kind of information. If I know a segment of users on my email list never open a particular type of email, it is better to just not send them that kind of email, both for the sender and recipient.
Regardless, I think Gmail killed tracking pixels by loading images through their servers anyways.
Google did not kill tracking personalized tracking pixels. All they blocked is the ability to determine the user's IP because you will get a connection from Google's proxy instead of directly from the user.
Those use cases are generally few and far between. They are the exception.
I've had my mail clients (and Gmail) set for years to not load external images, and occasionally get "we notice you haven't been reading our messages so we're going to stop sending them to you" emails from mailing lists that I do actually read.