Yes! Just go to the After Party > Thank You Cards page to send a thank you card to your guests. We'll automatically pull in the guests who responded Yes for your recipient list.
Note: if you want to send separate cards with different text for each guest, you will need to copy the card and make a new, separate card for each recipient (do not edit the card and then send again). Look for the "copy" link on the confirmation page after you send a card.