It's just unfortunate that mailing a physical letter is such a pain.
It could be worse: it was only 4 years ago I needed to cancel my HVAC installation with Sears Home Services and invoked my right to cancel the contract under WA law - and Sears required me to send an actual telegram (yes, the old-school, hand-delivered, all-caps short text messages) to their head-office address. I used this company: https://www.americantelegram.com/timedatestamp.php - to send it (and yes, it worked and I got out of the contract). But wow. I don't know how this can possibly be legal as it places an unnecessary undue burden on consumers unless there's some archaic legal carve-out for telegrams specifically?