I looked for this, but if it's what I think you're thinking of, they discontinued this service. You may be thinking of the one where they take your luggage to the airport, then print your boarding passes.
They now use DHL, and route the bags right to your house, but it's not cheap. $90 per piece each way. I got the info here
. Scroll down to where it says "luggage valet," then click that to expand that topic.