I'm pretty sure the feds have their marching orders and it's to go after the cartels and fentanyl dealers, not AAS, but there is a proposal to start imposing fines on the recipients of contraband in the mail like other countries do.
There's a part of the love letter that says something like "the penalty for blah blah can be up to $xxx".
CBP can actually issue fines, called an "offer in compromise" to immediately settle any trouble for small quantities of whatever illegal goods are found being brought in. Travellers who get caught with small amounts of drugs, fake bags, or other contraband at border crossings get them all the time. It's not an admission of guilt, apparently.
Something to put a little sting in the "love" letter.