[janusz]

From the BBC website:

The use of "invisible" tracking tech in emails is now "endemic", according to a messaging service that analysed its traffic at the BBC's request.

Hey's review indicated that two-thirds of emails sent to its users' personal accounts contained a "spy pixel", even after excluding for spam.

Its makers said that many of the largest brands used email pixels, with the exception of the "big tech" firms.

Defenders of the trackers say they are a commonplace marketing tactic. And several of the companies involved noted their use of such tech was mentioned within their wider privacy policies.

British Airways, TalkTalk, Vodafone, Sainsbury's, Tesco, HSBC, Marks & Spencer, Asos and Unilever are among UK brands Hey detected to be using them. But their use was much more widespread despite many members of the public being unaware of it, said [Hey's co-founder] Mr Hansson.

To be honest, the article reads a bit like a plug for Hey's services. Which of course doesn't mean the facts and analysis are incorrect.