Currently, you can make Packaging Exclusive to a SKU or customer. However, you cannot do the reverse and make a product or shipping method exclusive to a package type. So, you cannot use any flat rate methods and you cannot insure that a more fragile product is put in a bubble mailer instead of a poly mailer because they are both considered envelopes.

Allows you to use flat rate shipping methods.

1. Shipping Method > Packaging Type: Making Flat Rate Envelope Shipping Method exclusive to the Flat Rate Envelope.

Allows you to make sure a product that needs more protection is always put in exclusively bubble mailers.

2. Product > Packaging Type: "Making Product A" exclusive to the bubble mailer.