Ministry of Magic
Flying paper aeroplanes (referred to as "interdepartmental memos") are used within the Ministry of Magic. In "Harry Potter and the Order of the Phoenix" when Arthur Weasley takes Harry to the Ministry of Magic, Mr. Weasley explains that these took the place of the owls to minimise the mess. They are pale violet with MINISTRY OF MAGIC stamped along the edges of the wings. A variation on this method of communication is shown in the film version of "Harry Potter and the Prizoner of Azkaban", when Draco Malfoy sends Harry a note in class in the form of a flying paper crane.