What must Marketing Mail items not be?

Marketing Mail items must not be sealed against inspection because they are intended for bulk mailing and promotional purposes, which allow postal workers and recipients to view the contents easily. This transparency is essential for ensuring that the materials meet postal regulations and can be readily identified and processed during mailing.

Sealing against inspection could hinder the ability of postal services to verify that the items conform to required standards, which could lead to issues with acceptance and delivery. Options like being lightweight, sending by bulk, and being overall sized are characteristics that can vary based on specific marketing goals but do not directly impact the fundamental requirement that allows for inspection of the contents. Making sure that these items remain open to inspection aligns with postal regulations and facilitates smoother processing within the mailing system.