when does usps stop saturday delivery depends on the type of service used and the destination. USPS typically offers Saturday delivery for most services, including Priority Mail, Priority Mail Express, and First-Class Mail, with deliveries occurring as usual during business hours. However, USPS does not deliver standard mail or packages on Sundays, unless the service includes Sunday delivery, such as Priority Mail Express. Saturday delivery generally stops after regular business hours, and packages are typically scheduled for delivery the following Monday. Businesses and consumers should check the specific service details for accurate delivery timelines.