I particularly love receiving cards in "snail mail" - even though I pity the poor mail carriers this time of the year - I love stringing them up on ribbons around the house, and mostly, I love hearing from friends and family. These below are on my shortlist:
3 Holiday Snowman Christmas Cards by shesbattydesigns
Nastee Notes for the Holidays-HAPPY FREAKIN HOLIDAYS by Nasteenotes
damask Christmas greeting - small boxed set by mavoracards
Bright Snowflake- Set of 3 Holiday Cards by LindasPaperie
If you start somewhat early and do a few each day or several each weekend, you could get them all sent on time without stressing too much about the task.