United States Postal Service Shipping Equity Act This bill authorizes the mailing of alcoholic beverages by a covered entity in accordance with the delivery requirements otherwise applicable to a privately carried shipment. Covered entity is defined as an entity (including a winery, brewery, or beverage distilled spirits plant, or other wholesale, distributer, or retailer of alcoholic beverages) that has registered with, obtained a permit from, or obtained approval of an application from the Department of the Treasury pursuant to the Federal Alcohol Administration Act or the Internal Revenue Code provisions regarding alcohol, tobacco, and certain other excise taxes. The bill directs the U.S. Postal Service (USPS) to prescribe regulations: (1) requiring such mailing to be through a means that ensures direct delivery to a duly authorized agent at a postal facility or to the addressee, who must be at least 21 years of age and present a valid, government-issued photo identification at the time of delivery; (2) prohibiting such alcoholic beverages from being for resale or any other commercial purpose; and (3) requiring such covered entity to certify that the mailing is not in violation of applicable laws or regulations and to provide other information as directed by the USPS, including with respect to the prepayment of state alcohol beverage taxes.