First the letter was posted by registered mail from the ÖVEBRIA 2018 Exhibition (Klagenfurt, Austria) to Moscow. Then the letter was delivered to the International Space Station by the Russian "Progress MS-09” spacecraft. To document the delivery, on board the station, the letter was marked with all proper board seals including the Russian official “Russian Post. ISS. Russian Segment” round board post mark dated 10 July 2018, the day when the “Progress MS-09” spacecraft docked with the ISS.