If you are using plastic mailers, with or without bubble, chances are they were made with polyethylene resin. If so, then you are really sending out small stored energy sources with each shipment.
Polyethylene can be recycled over and over again, and when it is no longer recyclable, it can then be incinerated in a trash to steam plant. Air scrubbers are used so no toxins are released into the atmosphere.
Trash to steam operators love to burn plastics, as they generate the highest amount of BTU’s by mass versus any other material.
So make sure your customers are aware of the “green” aspects of plastic packaging, and burn baby burn.