[mcronce]

FWIW, https://www.mailaletter.com can do certified w/ return receipt, and there's also a service called Trim (https://www.asktrim.com) that can do cancellations for you. In my experience, some companies have explicit policy to not accept cancellation requests on your behalf from Trim, but it works for many.

[toomuchtodo]

I have been looking for something like mail a letter forever, thanks for sharing it.