In 1959, USPS delivery of mail by rocket took place for the first and last time. The USS Barbero, a submarine, fired an unarmed cruise missile carrying ~3,000 pieces of mail as its payload. It took 22 minutes to arrive to Naval Auxiliary Air State in Mayport. – WTF Fun Facts
Source: https://www.smithsonianmag.com/smart-news/mail-delivery-rocket-never-took-180963557/