A USPS is known as "U.S. Postal Service". They require commercial Mail Receiving Services to obtain a USPS 1583 for any client that requires them to receive, open, scan, ship, and dispose of their mail as per their request. A USPS 1583 needs to be notarized by the client (you). The Notary seal approves that you are authorizing the Mail Forwarding Service of your choice to receive your mail