I’ve never bought anything through mail order before, but I’ll give it a shot.
Things you sell that pass through the world to get to you are probably mail order. You order them and they get zoomed off to you, passing through all kinds of space to arrive at your door.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.