Abstract: An envelope includes a front wall having two lateral edges, a top edge, and a bottom edge; and a rear wall having two lateral edges, a top edge, and a bottom edge, the front and rear walls joined along their respective lateral and bottom edges; wherein the front and rear walls each have an outer ply including an outer layer including a propylene polymer or copolymer, polyamide or copolyamide, or polyester or copolyester, and an inner layer including an ethylene homopolymer or copolymer; and an inner ply including an inner and outer surface, including an air cellular or foamed material; the inner surface of the outer ply being adhered to the outer surface of the inner ply. A closure flap or other closure device, and one or more intermediate layers, can optionally be included in the envelope.