Expressing gratitude is always a good idea. The way you do reminds me of what we call "outreach" nowadays. Reaching out to people by mail usually works the way

Expressing gratitude is always a good idea. The way you do reminds me of what we call "outreach" nowadays. Reaching out to people by mail usually works the way you describe it. The only way most people do it wrong is that they don't say "thank you" first but they want something from you.