Moogle Lore

[MrThinker]

The mail delivery service extends to the First (somehow) and the local postmoogles do have blue poms.

Also Nutsy, leader of Clan Nutsy, has a blue pom as well.

But more on the specifics of your point, our mail is actually transferred to the First(which just so happened to coinicdentally develop a moogle based mail delivery system) by Feo Ul, who goes over to Eorzea's post-moogle to get the letters. Or at least that is what I think is implied:

Feo Ul was saying that the delivery moogles from “beyond”─wherever that is, kupo─have high hopes for you! I wonder if they have high hopes for me, too?