* for case quantity a foam case that separates each bottle is best, I have a few of these recycled from Craig’s list, folks get them when a commercial entity ships commercial product. The vinters club will ship collected club wine to contests like Winemaker Magazine or Kansas City. We have had some bad experiences using a store case with cardboard dividers.
* single bottle or two bottle shipments get wrapped in bubble wrap then sealed in a water tight plastic bag and then boxed, ,,, next is some padding as 1/4 foam and finally another box or tyvec envelope. (at work I ran the sample lab and occasionally shipped something to myself to check damage) I dont like bottles that have lots of ullage and go glug, I like synthetic (any position) corks, I look at the weather and assume in winter this part of the country might freeze.
* as an individual the shippers ask what it is, you don’t want to say wine! At work I could ship anything and the suppliers would ship to me lab quantities of hazardous chemicals via UPS. A bigger shipment as a case might come via motor freight.
* final thought, Do you have a local winery that has the connections to ship? (Part of the issue is drinking alcohol is a state regulated item) Do you know the person at work who runs shipping?