This branch of the United States Postal Service is called the San Luis Rey Office because of its proximity to the historic Mission Church. It is located in the Marketplace Del Rio shopping center near the Stater Brothers grocery store. It sells stamps and offers a variety of options to mail a letter or package. Its priority mail service has become a popular, affordable way to mail a package because, as its motto says, "if it fits, it ships" regardless of the weight of the package. It also offers overnight shipping and mails to almost any country in the world. More information may be found on its website.