Well linkpearls as I understand (if it's anything like in FFXI) are physical objects that would theoretically have some kind of distinguishable markings on them or something (otherwise how could you tell them all apart). So with that in mind if this were done through an LS you wouldn't need to have a code word or anything like that (since code words are easy to obtain if you know how, or have the money to bribe/extort). Bearing a linkpearl from a reputable courier service would be enough in most cases, sort of like a badge or an ID card that says "this guy is trustworthy" especially since the people who control the Linkshell can create and destroy Linkpearls, which means if one were lost or stolen it could be destroyed and a new one created. That was how I understood the way they worked anyways, correct me if I'm wrong.
On a side note, aren't Moogles technically the canon courier service in the game via Mog Mail? I mean you can send letters, packages, and gil through them. The only downside is you can't use them to contact people you don't know, so I guess this could be where a freelance courier service would come in handy.
On a side note, aren't Moogles technically the canon courier service in the game via Mog Mail? I mean you can send letters, packages, and gil through them. The only downside is you can't use them to contact people you don't know, so I guess this could be where a freelance courier service would come in handy.