The Articles Of Confederation gave the united states the power to establish the U.S. postal service, as well as make treaties.
https://www.history.com/topics/early-us/articles-of-confederation
<em>"But Congress would exercise considerable powers: it was given jurisdiction over foreign relations with </em><em>the authority to make treaties and alliances</em><em>; it could make war and peace, maintain an army and navy, coin money, </em><em>establish a postal service,</em><em> and manage Indian affairs; it could establish admiralty courts; and it ..."</em>
<em>https://www.monticello.org/site/research-and-collections/postal-service</em>
<em>"Benjamin Franklin was appointed as postmaster general. </em><em>Despite a clause in the Articles of Confederation to establish a federal post office</em><em>, Congress waited until October 18, 1782, to pass "An Ordinance for Regulating the Post-Office of the United States of America.""</em>
