Interdepartmental memos are a method of communication between departments at the Ministry of Magic. They usually take the form of purple paper aeroplanes, with "Ministry of Magic" stamped along the side. The Ministry used to employ owls for this purpose, but discontinued use because they left droppings everywhere which was somewhat disconcerting for Ministry workers. These memos go in the lifts, and leave when their levels come. One of these memos informed Arthur Weasley of the regurgitating toilet discovered in Bethnal Green.