I see Christmas as an annoying annual inconvenience. I wasn't necessarily a fan of it back when it "meant something" but now it's so damn commercialized and all it stirs up is stress, consumer debts and guilt that I really want no part of it.
However, I tend to keep those views to myself and just quietly ride it out.
But all that aside, as a matter of basic ETIQUETTE, I too would never send a promo or business communications on Christmas.