Magazine packaging is the technique of preparing and protecting printed magazines for mailing or shipment. Most magazines these days are mailed in a polypropylene or polyethylene wrapper. There are more environmentally-friendly alternatives, though.
"The first and most obvious alternative to polythene is paper envelopes. Unfortunately (for paper and envelope manufacturers at least) mailing subscription copies and packaging newsstand copies (particularly promoted issues), in a paper envelope is probably the least practical solution available and almost certainly the most expensive. There are a very small number of mailing houses out there who do have wrapping machines capable of mechanically packaging a magazine in a paper outer, but sadly the cost of the paper combined with the cost of the physical wrapping makes this option totally impractical and unaffordable for probably every publisher currently trading..." 
However, for someone just shipping a used magazine to a buyer on eBay, for example, then sandwiching the magazine between a pair of thin cardboard or card-stock paper and sticking it in a long envelope should be sufficient.