I think the email thing is because I don't have it written in my email address that someone else reads my emails. So while I could tell my friends or family about someone else having access to my email, I couldn't tell strangers or people who contact me for the first time.
Even when I have asked someone to check my email for me, I asked them to tell me the sender and subject line, not to open them until I said I was fine.
It's like being recorded and listened to by someone permanently. You might start a conversation with someone who doesn't know. Unless you carry a sign that says so, you might not realise someone is going to say something very private until after they have done it, and oops, someone else heard it all.
I believe it's actually illegal in France to record someone without their permission. I think it's not even accepted as valid evidence in trials, so the common movie plot of someone hiding a recorder to trick the killer wouldn't work.
So yeah, anything second hand like that would be bad, because it's somebody else's privacy, and unless expressly told I can share a specific thing, I assume I can't share stuff (which is why I ask people if I plan to). I might share something anonymously ("this happened to someone") but never specifically.