Interesting indeed. I would never have guessed this. But I guess when we put our words in the written form, they can in essence be trudged up and used as evidence for what we said (or didn't say).
I'm actually trying to get away from e-mails and texts and call or speak in person more. I don't feel I'm very good at expressing tone in e-mail and sometimes we can get ourselves in trouble as our written word isn't taken in the manner it is intended?