Full Terms & Conditions available here: https://www.delta.com/content/www/en_US/traveling-with-us/planning-a-trip/booking-information/online-booking/etickets-certificates-ecredits/gift-cards-term-conditions.html
Call 800-221-1212 for balance information and customer service. eGifts and Cards may only be used for the total purchase price of air transportation, including taxes, fees, and surcharges imposed on the air transportation. They may not be used for any additional fees (including baggage fees) or for any other products or services (including class upgrades, in-flight purchases, premium seating, mileage booster, SkyMiles Cruises, cargo, hotel stays, or car rentals). eGifts and Cards may only be used for travel on Delta Air Lines marketed flights, including those operated as Delta Connection® and by Delta Air Lines codeshare partners with a Delta Air Lines flight number. Tickets purchased using eGifts and Cards are subject to the applicable Delta Air Lines Contract of Carriage and fare rules (including change penalties). If redeemed at www.delta.com, a maximum of three forms of payment (including eGifts or Cards) can be applied towards a single transaction, regardless of the number of tickets purchased as part of that transaction; if redeemed through any other method, a maximum of three forms of payment (including eGifts or Cards) can be applied toward a single ticket. eGifts and Cards can be used with other eGifts and/or Cards, but cannot be used in conjunction with any other certificate, voucher or credit towards a single ticket. eGifts and Cards are not reloadable and do not expire. No service or inactivity fees apply. eGifts and Cards, including those that are lost, stolen, or destroyed, will not be replaced by Delta for any reason. eGifts and Cards are not refundable and cannot be redeemed or exchanged for cash, check or credit except where refund or redemption is required by law. eGifts and Cards are issued by Delta Gift Cards, Inc. (“Delta”), an affiliate of Delta Air Lines, Inc., that is authorized to issue eGifts and Cards for sale by Delta and Delta-licensed vendors to be used toward the total purchase price of air transportation on Delta Air Lines marketed flights.