Wrote to a composer a few years ago and pianist recently with pretty focused things I wanted to compliment, and they both clearly appreciated it because they sent very long, considerate responses (longer than what I had sent initially!)

Seriously it makes their day. They’re people too!

I have corresponded at length with composers who seemed to appreciate the interest. On the other hand, I know a composer (not even that famous, just successful enough) who has his copyist answer all correspondence with stock replies, since fans don't do anything for him and just annoy him; they aren't part of the ecosystem of commissioning works that is how he gets paid.

I had this experience some years ago writing to an author, too. Long reply back.