alt Hacker NewsThat just means the person sending the message didn’t bother to proof read their message before sending. And you don’t need to be on an iPhone to mistype a message.
A simpler explanation was that it was a shameful advert injected into the end of people’s emails.
I guess, it was probably intended as the second one (it was also the default email signature, so advertising that feature, as well), but its usefulness was definitely in the implied warning.
Mind that a written message used to be the gold standard for expressed intent, which changed quite radically with smartphones. (Historically, this development is probably an important prerequisite for the acceptability of LLM generated text, I guess.)