Ask HN: How to Sort to 1.000 Destinations?

I work for a parcel delivery company based in Europe. To reduce CO2 in our network, we are looking for different solutions. One of these solutions is to deliver parcels at a shop instead of a home address which will result in less driving. But here comes a challenge: with over 1.000 shops we already use I need to find a way to sort parcels to 1.000 destinations, even 1.500 or 2.000 in the future. Beside sorting out to 1.000+ destinations, we are talking about roughly 100.000 parcel per day (future growth included). Luckily, the solution I'm looking for is only needed for "smalls", parcels up to 400x400x400mm max Any idea how to solve this?