The landlord's problem is "mailing". The post office, of course. It's not called "mailing" except the post office.

Understand the landlord's meaning, or find a freight company, search online, make a phone call, and they will provide on-site service.

Supplementary answer:

If the landlord must ask for on-site service, the best way is to find a freight company, which is the cheapest way;

If you don't necessarily need door-to-door service, the cheapest way is railway consignment, but you need to send the goods to the station consignment office and pick them up at the station yourself.