I have sent many thank you letters (via snail mai to the PDs after interviews and have yet to hear anything back at all. All of my interviews have been extremely poker-faced, thank you for coming, if you have any questions, etc etc. Very difficult to read. Especially since I am a DO student, and all of my classmates are getting calls and emails from the osteopathic programs this time of year about their rank, etc. Frustrating!