U.S. Postal Service retail services that involve interacting with a clerk are not available on Sundays; however, some postal locations with mailboxes leave their lobbies open so that customers can still access them on Sundays. These locations may also have automated machines that provide some postal services.
Hours vary by location, but U.S. Postal Service retail hours are generally 9 a.m. to 5 p.m. Monday through Friday, and certain locations have limited hours on Saturday. Some locations have automated machines that accept letters and packages and sell stamps after hours. Some postal services are also available off-site at certain retail and grocery stores. The USPS website has a locator for finding post offices and approved postal providers.