Letter Pack: Similar to a large envelope, but can be made of thin plastic, is a flexible style envelope-used for shipping documents or small, items that are too big to qualify as a standard letter but do not require a full box.

Packages: Typically includes boxes, padded mailers, plastic envelopes or tubes (cardboard, corrugated), bottles, drums, and other enclosures designed to hold the product. 

Magazine: A magazine is a printed publication, typically bound in a softcover format, that contains articles, images, advertisements, and features. 

Postcard: A postcard is a flat, single piece of thick paper or thin card-stock used to send a message without an envelope. Rectangular and rigid enough to mail without an envelope. It's one side usually has space for a short message and address and the other side may feature an image, photograph, or design. It's often mailed at a lower postage rate than letters.

Packages: A box or irregularly shaped mail item.

Pallet: A large shipment, usually consists of more than one box or package bundled on a wooden pallet base.