That's a good question. I'm not too sure to be honest, might be a good one for Joel or Computershare for confirmation.
I'll take a punt that it will have some sort of tracking so that Computershare can say with certainty that the letter was sent and in turn received, but i'm just guessing. It also states in the announcement that it's being sent 'via an express network' which implies some sort of tracking/registering, but again I'm guessing.
