How effective are mail campaigns for TV shows?

Let’s say I get mightily pissed off about something on Buffy the Vampire Slayer, and so I organize about 50 of my closest friends and every day we all send in at least 2 postcards, if not more.

  1. Who reads the postcards?
  2. What do they do with the postcards?
  3. Does the network even care? Especially if it’s a relatively small number?
  4. Do the producers even care?
  5. Is there any chance it’ll ultimately make adifference?

FWIW–I’m in a huge debate right now with some people, and my stance is basically “Send them if you want, but don’t think it’s going to make a difference.” Right now though, I’m just talking out of my ass, I really have no idea how the whole system works.