Blasé, maybe, but yes. A few days ago, I wrote a short "thinking of you" email to someone I hadn't spoken to in 3+ months. It was wonderful. Going to write at least another three today. Will follow you if you reply with a commitment to write just one.
https://twitter.com/kanyewest/status/989556813849739264 …
Nah. Anything that expresses your genuine caring for/appreciation of them works. Try to not hold back too much, though. Really summon up how it feels to have this person in your life before you write. 