I wasn't aware of this, but I still don't think this is a compelling analogy. I doubt that these companies were able to efficiently parse the content of these messages in order to manipulate the distributions of certain messages, for example. Further, there's simply no way that post had nearly the same share of communication as do digital systems today (most communication was certainly by word of mouth and print).

The majority of communication was still local - and importantly, B/D India Company wasn't opening and reading and censoring all the letters they were transporting.