There very well might be, but my understanding is that courts are not likely to draw decisions on email-related cases based on precedent set on mail-related cas

There very well might be, but my understanding is that courts are not likely to draw decisions on email-related cases based on precedent set on mail-related cases (although like all things, that interruption is likely to vary country to country). Namely, since email is not sent through a government postal service, and is much more akin to a private courier.