Merchants may ship items from any dock. In order to ship an item, a merchant must find a smuggler and 'hire_ship'.
The merchant will be given a shipping container to put his or her goods to be shipped in.
Then, the merchant can ship the items at any dock (the smuggler will send a freighter to you) by using 'shipto <player>' or 'shipto <player> <condo>' where <condo> can be sluis, ds, soleada, or hm (if the person has an HM home).
A shipping fee does apply unless the merchant also has diplomat mail services.