Read Receipts are invasive, because they signal when I read it - which might well not be when I want to reply. I could read an email today and then decide I'll reply tomorrow or next Wednesday, because reasons; but the sender will see the read receipt and just assume I hate their guts for not replying immediately to the Most Important Person In The World (i.e. them).

So I turn them off as a matter of routine on all my accounts.

read receipts just mean you opened the message, not that you actually read it. It's a terrible misnomer.

Yes! +1 And it's possible to disable Read Receipts and a lot of people do. A lot of people mangle beacon pixels too.

Oh yeah, the thing I always turn off or filter out because the last thing I need is another way spies and hackers and ad men can track every waking moment of my life.

That was another groupware feature that was great for small orgs and terrible for the general net.