RCM suggests that you write a message cheering on your clients that celebrate Christmas.
Example: Wishing all our valued real estate clients a joy-filled Christmas filled with warmth, laughter, and the comfort of home. May this festive season bring you an abundance of happiness and a prosperous new year ahead.
Bonus example: I love ugly Christmas Sweaters! I have one that has a reindeer drinking a beer. It's my favorite Christmas Sweater and I look amazing in it.