I know this is old post, but I just came back 3 days ago with 12 bottles of wine (in a wine bottle shipper box) without any issue at MIA, but of course, I have to spend an extra 20 minutes waiting for my bags (the go trough x-ray before arriving at the bell), plus another 20 minutes to "recheck" my box at customs, they will send you to the yellow dots when they see you with any kind of box.