The bill in your hand can legally prove that I did send the courier. It is the courier's dereliction of duty to leave the courier at the doorman's office and not sign for the courier. If he doesn't admit to receiving the courier, the courier is not clear and should be responsible. Therefore, everything that is guaranteed must be done according to the procedure, and whatever is signed will be signed. Even if you accept it, you should ask the doorman to sign it, and it will be fine if you sign it.
Postal Law of People's Republic of China (PRC)
Forty-sixth postal enterprises are not responsible for the loss of ordinary mail. However, ordinary mail losses caused by intentional or gross negligence of postal enterprises are excluded.
Article 47 Postal enterprises shall compensate for the loss of vouched mail in accordance with the following provisions:
(a) if the insured mail is lost or completely damaged, it shall be compensated according to the insured amount; In case of partial damage or shortage of internal parts, the actual loss of the mail shall be compensated according to the ratio of the insured amount to the total value of the mail.
(2) If the uninsured vouched mail is lost, damaged or the internal parts are short, compensation shall be made according to the actual loss, but the maximum amount shall not exceed three times the charge; If the registered letter is lost or damaged, it shall be compensated at three times the charge.