Cardboard Mailers from ColomPac® all include reliable peel & seal closure, fast assembly, paper-cut-free edges, and easy-open tear strips as standard. CP 065 Postage Optimized Courier Packs are letterbox friendly cardboard mailers which reduce returns and postal costs. CP042 CD Mailers are premium white CD mailers with windows for sending CD cases with accompanying letters. CP037 Flexible Mailers are extra-secure white wrap-around mailers with a tamper evident double seal and double corrugated walls throughout. All cardboard in these mailers is FSC approved.