I would check that assumption. Most letters I have sent were required because some service was living in the stone age, or making my life difficult.

For example, to cancel my gym membership, I had to mail a notorized document to their corporate office. The entire purpose was to discourage and inconvenience me. I'm sure they toy with the idea of making cancellations in-person only, at an office on the peak of Everest. I'd just assume that letter arrive flaming as printed on high quality paper.