--> How do I get the mail in the trough?

First stick your hand into the mailbox.

The mailbox leads right into the llama's trough.

Maybe if you made the llama happy, it wouldn't be so offended by your rooting
through its food.

Some food would brighten up his day.

The llama treats you should have bought at the beginning of the game will do
well. (Note: Even before you exit your house, a salesman will offer to sell
you a bag of llama treats.)

Empty the bag in the mailbox.