Of late, Facebook is like my mom. It keeps pointing out friends that I have not been in touch with in a long time. "Maybe you should send so and so a message. I'll bet he/she would be happy to hear from you," said in the same tone of voice that she used when she would press me to write thank you notes. (I may or may not have mentioned to you that BBFK is a beautiful thank you note writer. A card from her will make you feel like a Million Bucks.)
As an awkward person of no social graces, I ignore Facebook's suggestions and my mother's and almost never send thank you note. Bad dog! No cookie! I count myself as lucky to have friends all things considered. And such fine friends at that.