Ans. To request for a refund for an unused ticket you need to call the Delta sales representative on 8008470578 within US or Canada. For other countries please call the local office of Delta Airlines in your country. You can submit flight coupons and paper tickets to the Delta Airlines refund Department on the below address. "Via U.S. Postal Service Delta Air Lines, Inc. Passenger Refunds P.O. Box 20537 Atlanta, GA 30320-2537"