Which processing category includes postcards and letters?

The processing category that includes postcards and letters is the Letter category. This category is specifically designated for items such as standard letters and postcards that fall within certain size and weight parameters. The Letter category allows for efficient sorting and handling at postal facilities, as these items generally have a standardized format that makes them easier to process.

Items classified under the Letter category typically measure a maximum of 11.5 inches in length, 6.125 inches in height, and must be within a certain thickness range. This categorization helps streamline postal operations by enabling the postal service to use specialized machinery designed for handling letters and postcards. Therefore, understanding these attributes is crucial for anyone involved in postal operations to ensure items are sorted and processed correctly.