Which postal category includes letters over 11.5 inches long?

The category that includes letters over 11.5 inches long is indeed Packages. In the context of postal classification, a letter is classified based on its dimensions. Standard letters are generally classified within First-Class Mail, but there are specific size restrictions that determine whether an item qualifies for that category.

When items exceed standard mailing dimensions, such as being longer than 11.5 inches, they transition into the Packages category, which encompasses various types of mail and parcels that do not meet the criteria for letters or flats. This category is designed to accommodate larger items, allowing for a wider range of packages to be shipped effectively.

By classifying items appropriately, postal services can ensure efficient processing and delivery. Other categories, like Flat Rate Boxes, have their own size limitations and specific rules regarding contents, while Media Mail is meant exclusively for educational materials and has different restrictions unrelated to letter dimensions. Therefore, recognizing the transition point in size is crucial for understanding how the postal system categorizes and processes different forms of mail.