The most prevalent mail-carriers in the British wizarding world are owls. A wide variety of owl species are used, including Screech, Barn, Tawny, Brown, and Snowy owls, each possessing the innate magical ability to deliver letters and packages. These birds are capable of carrying items ranging from small scrolls and letters to larger parcels and even broomsticks, which are typically slung beneath them. Mail-carrying owls are often identified by the letters or packages tied to their legs. A distinct system exists within the Ministry of Magic for internal communication. Instead of living creatures, the Ministry employs enchanted paper airplanes, colored pale violet, which function as 'Interdepartmental Memos'. These memos fly through the Ministry's halls, folding and unfolding themselves to deliver messages between departments.
The primary magical property of mail-carrying owls is their preternatural ability to locate the recipient of their mail without needing a physical address. A sender need only attach the letter and name the recipient for the owl to find them, no matter their location. This ability works even if the recipient is mobile or in a magically concealed location, as demonstrated when Hedwig successfully delivered mail to Harry Potter at the Leaky Cauldron and when Harry sent letters to the fugitive Sirius Black. Owls are notably tenacious, often flying through difficult conditions to complete their deliveries. Upon delivery, it is customary to pay the owl a few bronze Knuts for its service. Owls deliver all manner of items, including personal letters, subscriptions to newspapers like the `Daily Prophet`, official correspondence such as Hogwarts acceptance letters, and ordered goods from shops like Diagon Alley. The Ministry of Magic's enchanted memos operate differently. They are bewitched to fly directly to their intended office or individual within the Ministry building. They are less secure than owls, as they can be physically caught in mid-air by individuals other than the intended recipient.
The precise origin of using owls for mail is unknown, but the practice is ancient and deeply embedded in wizarding culture, predating other forms of magical communication. The existence of establishments like the Owl Post Office in Hogsmeade indicates a long-standing, organized system. The reliability of the owl post system became a significant factor during the Second Wizarding War. In 1995, Dolores Umbridge, as Hogwarts High Inquisitor, began illegally monitoring all incoming and outgoing owl post at the school in an attempt to control communication and discover Harry's connection to Sirius Black. This forced The Order of the Phoenix and members of Dumbledore's Army to seek alternative methods of communication, such as using the Floo Network. By 1997, with the Ministry of Magic under the control of Lord Voldemort, the general owl post was heavily monitored and no longer considered secure for sensitive information.
Mail-carriers are fundamental to the narrative of the *Harry Potter* series, driving the plot and connecting characters across vast distances.