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.

"Letters come from all over the world," says Andreas Vogt, who empties the letterbox and founded a citizens' initiative to protect the old chestnut tree, and now, the new one.

"Some people write very emotional [notes] about death, birth, weddings, loneliness, or personal fate," he says. Some correspondents want to know more about protection of the environment. Vogt sits down every day for up to two hours to answer them all.

He remembers one woman who wrote from a nursing home. She could not walk and wrote that she would love to come and visit the tree, but just couldn't. So Vogt and his wife drove to see her instead. "It was a very moving moment", Vogt reports, "the woman had collected many articles on the tree and wanted to know more."

German Chancellor Angela Merkel and model Heidi Klum have sent autographed postcards to Juechtwind. A lady-in-waiting of Britain's Queen Elizabeth reportedly wrote a note on behalf of the queen. Other letters came from Japan, New Zealand and the United States. Century High School in Sykesville, Md., wrote in 2008. A teacher of German there sent a note about the school planting a small chestnut tree on campus to increase awareness of trees and the climate.

Some people who write to the new chestnut tree in Duesseldorf will receive an answer from 11-year-old Leni Classen as Erona. She's just started her "tree-internship," as Vogt puts it. He organizes benefit events and readings of fairy tales under the tree. And in the fall, people gather to rake the fallen leaves.

Vogt hopes for more. "I would very much appreciate if Barack Obama sent a greeting or an autograph," he says. "And we are looking for partners in the U.S. who want to start a similar project [with their own tree]." Britta Toellner, a spokeswoman for the Deutsche Post mail service says, "The postman cycles a detour of 2.2 kilometers per day to deliver mail to the tree. Many letters are beautifully decorated," she says.

Copyright 2016 NPR. To see more, visit