I enjoy the tradition of sending out Christmas cards to all my friends and family each year, but some of them don't send cards back. I completely understand that not everyone has the time or desire to send cards, so it doesn't bother me at all. However, I've had a few people I've sent cards to text me to say they received my card and they are sorry that they aren't sending one in return. What can I say back that doesn't sound offensive? I thought about saying that I don't expect cards in return and I know how busy this time of year can be, but I don't want it to sound like I'm criticizing their time management skills.