from what i know the only drop off point is at their respective offices, which is city center, santiago. also, they will not deliver, they just call you and you have to pick it up at their office. at least this is how it works in POP, i send i receive letters for the pharmacy that way. an envelope is 100 pesos right now (a letter, documents and so on). packages go by weight. but i have sent quite juicy envelopes too, fat and heavy, still 100 pesos.