KNOXVILLE, Tenn. (AP) — During a year when many feel disconnected and technology is the only thing keeping people together, Knoxvillian Jenny Sich's app Cardlet is rekindling relationships.

Using the Cardlet app, senders can mail high-quality, physical greeting cards with AR surprises and voice messages. Recipients scan the cards and make the "magic" cards come to life right on their screen.

Sich and her husband Matt Sich, Cardlet's Chief Technology Officer, worked on the greeting card delivery service for nearly a year and a half before releasing the app in May. Although there are other apps...