@Anonymous wrote:
Would overnigting via UPS or DHL give you the same legal protection? When sending, I would require a signature as well.
Yes it would. Anything with a legally trackable and proof tracking will be acceptable. The Certified Letter is the least acceptable legal proof in court. That's why people who use proof of mailing tend to be disappointed when it doesn't hold up in court, that's mostly for your own record or dealing with customer service for a returned order or something.