Kati Salo & Asko Keränen are sending greetings the old fashioned way, before there's been whatsapp, twitter, Facebook. The postcard contains a download code to their 4 song debut EP as a duo. If you shouldn't receive such a card in your letterbox, you may find it on their merch where ever they gonna play.
But even without the postcard you get their first songs, here, or here