What is the requirement for mail that includes perishables?

The requirement for mail that includes perishables is that it must be labeled properly. Proper labeling is crucial because it ensures that everyone handling the package is aware of its content, specifically that it contains items that can spoil or deteriorate. This labeling typically includes information about the contents, special handling instructions, and any temperature requirements. When perishables are not labeled correctly, it can lead to mishandling, delays in delivery, and potential spoilage.

While proper handling, storage, and transportation play vital roles in the preservation of perishable items, labeling serves as the first line of communication about the package's needs. Ensuring that the mail is clearly labeled helps maintain the quality and safety of the perishables during transit.

In contrast, the other options focus on specific conditions that, while important for certain scenarios, do not universally apply to all perishables or may not reflect the primary requirement. For example, refrigeration and expedited shipping are relevant for some perishables, but not all. Likewise, the notion that perishables must be sent domestically is incorrect because many perishables can and are shipped internationally with the right precautions in place.