What is the use of the blue post box?

The blue post box is primarily used for sending letters and parcels via the postal service. It is typically found in public places and allows individuals to deposit their mail securely for collection by postal workers. The blue color often signifies that it is designated for a specific postal service, such as airmail or express delivery, depending on the country. Using these boxes helps streamline the mailing process and ensures that items are dispatched efficiently.