What?
Christmas cards are generally made of heavy paper or light card.
How?
Most cards and their envelopes can be placed in the household recycle bin but any embellishments such as ribbons should be removed first. If the card is glittery then it cannot be recycled but will make for great cut-outs for arts or making other cards.
Also, if the envelope contains a film window, this too should be removed prior to placing in the recycling bin.
General Comment / Tip
Old cards could be use for arts and crafts.