I used to write Hope all is well with you and yours, but then it occurred to me that this could be regarded as thoughtless because I didn't know their circumstances. This year I made a decision to stop sending cards to people where the only contact I have with them is by Christmas cards. I mean the cards that are sent to people who I will never see again or don't hear how they are via someone else.
This doesn't apply though to most family members. My aunt died last year and my parents had fallen out with her when I was a child. I'd only met her a few times since then, although I knew how she was doing through another aunt (her sister). For some reason that I can't remember now, when I started sending Christmas cards as an adult, I decided to send her a card every year. When her house was cleared, it turns out she'd saved every card I had sent her - and thank you letters from before the falling out. I am glad I sent those cards.
There are two old friends I send cards to that I haven't seen for years, but I know we will meet again sometime. I still exchange birthday cards with one of the one of them who was my best friend at school. I rely on her birthday card to me to let me know if anything has happened to her parents because I also exchange cards with them and don't want to send them a card only to find out one has died.
On most cards this year I just added something along the lines of Wishing you a Happy New Year for 2016.
I just don't think I should send a card to someone when I no longer know anything about them.