Real World article(written from a Production point of view)
The United States Postal Service is the United States of America's mail service.
A thirty-three cent Star Trek stamp was released on 17 September 1999 as part of its "Celebrate the Century" initiative. Later that year, Hallmark also distributed the stamp as the centerpiece of a Christmas ornament.
On 22 June 2016, it was reported that four new Star Trek stamps stamps would be available for pre-order in August 2016 with an expected release date of 2 September 2016. 
On 2 September 2016, they were released at Star Trek: Mission New York with Walter Koenig in attendance. United States Postal Service (real world)
1999 Hallmark stamp ornament