I know many of you are thinking it....

[BloodLotus]

You'd still both have to leave your current tasks to go to the mail box to send and receive the items. If you're going to do that, one of you might as well just teleport to the other person.

So I teleport from humblehearth to limsa (3) to make a friend stop grinding to trade iron in the blacksmith guild, teleport back to gridania (3) and walk to humble to keep mining.

In case you didn't know, 1 anima regens every 4 hours.

Or

I can run to gridania mail off the ore, my friend can pick them up when he feels like it and I can walk back to humble to mine more.

Then I have anima to use on more important things like going to camps near nm spawns.