I am not a great writer of fan letters, but I have from time to time written to well-known authors and I have always had a reply – indeed sometimes a lengthy one. One letter I sent simply addressed the name, famous author, and the town got through safely and prompted a useful reply. All sorts of writing can prompt communication to the author. It is not just books, articles too may do so and some even encourage responses by ending with an email address or link of some sort. The same with talks at an event or on radio.