The swap that looks close
cartons for soft goods is the usual substitute for mailing bags on a weekly order, and it is the wrong one. A carton around a soft item adds board you post and store for no stiffness you needed.
Packaging Wholesale lists Mailing bags separately because the jobs diverge as soon as the goods are on the bench.
What the right line actually does
Mailing bags are the weekly outer for soft goods that do not need board.
Grey mailers are opaque, recycled-film and described as recyclable. Coloured bags are on the same range.
If you have already mixed them
Using the carton because the bag size is out teaches the bench the wrong outer.
On Packaging Wholesale, orders that include Mailing bags and are placed by 3pm are dispatched the same day. UK delivery is free on orders over £50 ex VAT. Stocked items can be returned within 14 days.
Open Mailing bags when you already know this line. You buy a pack of bags. The count is on the product. Packaging Wholesale will still dispatch an order placed by 3pm on the same day.