No, you don't need to stand in a particular spot or wait around at all. As long as the character name and server you provided are correct, the supplier can complete the delivery regardless of where you are in the world. You can be inside a dungeon, questing in a remote zone, sitting in a capital city, or even fully logged off — the Coin Gifting process goes through all the same. There's no need to interrupt your gameplay or camp a mailbox. Just keep playing as usual; the gold will be waiting for you the next time you check your inventory.
