The USPS certified mail works through a residential address if there is no one at home in order to take the delivery. Then the USPS will leave you with a reminder slip in your mailbox. So by looking at the sleep, the receiver will get an idea that your mail has been left at the USPS office. The mail which is held at the nearest local post office the receiver will go to the nearest post office and pick the mail directly. The package will be provided to the individual only if they provide the signature when they pick up the mail or package.
If in case this process does not work then you can go for an alternative way in which you can pick up the letter box after 5 or even up to 7 days from the nearest post office if you are busy. There will be a second delivery slip provided to the individual which will be sent by the post office as the second time certified mail reminder.If in case you did not collect the package within 5 to 7 days then there is a third option.USPS Tracking Package
The USPS will send you a 3rd final attempt of delivery slip which will be given to you if you did not respond for 10 to 12 days. When the third notification has been sent if the receiver does not respond then the main will be sent back to the address given on it.