Privacy is not all or nothing. It is about context. Information _x_ may be shareable with person _p_, but might be an invasion of privacy if it is shared with o

Privacy is not all or nothing. It is about context. Information _x_ may be shareable with person _p_, but might be an invasion of privacy if it is shared with other people. So "not putting deeply private stuff in an email" is not practical in general. Even shallowly private stuff would become deeply private in a different context.