I have no idea how they did in South Africa, but in British India, letters and parcels were carried by two different systems outside the cities. Letters were carried by runners in the 19th century (and well into the 20th in many places, where there no roads), while parcels were carried by horse or bullock cart.
The British Indian post office used distinctive cancels for the parcel post, and so did some of the Indian States. This example from Jammu & Kashmir only shows the bottom of the (rather large) cancellation but with PAR indicating PARCEL at the base

on the 2 Anna yellow on deep green of 1883-94. (The basic letter rate at the time was ½ Anna.)