As a teenager, I found Terry Pratchett’s email (in a newsgroup IIRC?) and sent him a thank you note. I told him how much his books made me love reading. He answered me with a short and sweet email. It was an important internet moment for me!
As a pre-teen i sent him an embarrassingly pretentious and ungrammatical fan email and was horrified to find a reply from him years later when migrating mail providers.
You can't leave it there! What did he say? Was he polite, helpful, amusing, amused, etc.?