GADO was a bus company operating in the northern provinces of Groningen and Drente: N.V. Groninger AutobusDienst Onderneming (Groningen Bus Service Company Ltd.). It was based in Hoogezand, a town in Groningen Province, and from 1958 in the provincial capital Groningen. The company, for a long time, was owned by the Dutch national railways (NS).
From what I can find, the stamp paid for press items transported by bus. "Pers" is the Dutch word for press. I think the addressee is Red - "Het Nieuwsblad." This was a newspaper. Red, most likely is either the editor (redacteur) or the editing office (redactie) of that newspaper.