Letters to the Pope should be mailed to the following address: His Holiness, Pope Benedict XVI, Apostolic Palace, 00120 Vatican City. The Pope also has an email address, firstname.lastname@example.org . This being said, however, it is unlikely that the Pope will respond to, or even read, you letter. As a person of great importance, the Pope has his mail handled by others and if your letter can get past them, only then will it reach the hands of the Pope himself. You can write or e-mail to the given addresses anytime you want, but be prepared to receive no responses.