Ryan

There are multiple letter that can be delivered, each trigger of the experiment will deliver one of them. Ive only managed to get three delivered so far. But the ones I have received each provide a clue on how to solve one of the puzzles in the manor. Such as the paired pictures puzzle, or the billiard room puzzle.

So if you're struggling to figure out what to do with a type of puzzle, maybe focus on the letter delivery experiment and you may get a clue.