[oddlyaromatic]

> So I can understand that Mozilla might want to keep themselves off mailing blacklists

So can I, but the desire/need to do this does not imply a "right" to track the opening of messages in the manner initially planned. The reader does however have a right to privacy, whether they link know about a 1x1 image and its effects or not.

Email deliverability is a giant pain to have to deal with, of course, so the motivation to overlook this small sacrifice of privacy is pretty high.