There's a chestnut tree in a nature reserve in Duesseldorf, Germany, and it has a mailbox. People have sent it 5,500 letters and postcards since 2007.
They wrote to the spirit of the tree named Juechtwind or "where the wind always blows," and every piece of mail was answered.
Last year the almost 200-year-old tree got sick, struck with a fungal disease, and had to be cut down.
But now tree counseling has been taken over by its younger brother named Erona, which means summer breeze.