The phrase "to send a card" means to mail or give a special note or greeting to someone on a special occasion or to show appreciation or sympathy. Full definition
Our clients often send us cards of appreciation, encouraging letters, and family updates! (believemidwiferyservices.com)
They even sent me a card in the mail when one of my rats passed. (griffinexotics.com)
But, each and every year her awesome husband remembers to send me a card with a photo of the kids and a beautiful saying and photo of my friend on the back. (littletechgirl.com)