Here are the T&Cs...Got it as an email with a link to sign-up via Delta.dumb website...

https://click.o.delta.com/u/?qs=25ef...6bbb034080d815

Terms and Conditions

eCredit: This eCredit is valid for the dollar amount indicated above. When the ticket is issued in currency other than USD, the value should be converted to the currency of the country of payment at the Bankers Rate of Exchange in effect on the date of ticket issuance, and the rate of exchange must be indicated on the ticket. This Delta eCredit may not be altered by the agent of any carrier named herein. The recipient of the offer must book AND travel within 60 days of receiving the birthday e-mail offer using the enrollment link contained in the e-mail. This promotion ends by December 31st, 2023 (ending 11:59:59 PM, U.S. Local Time on 12/31/2023). This Delta eCredit may not be altered by the agent of any carrier named herein. An eCredit will expire 180 days after the date of issuance. The eCredit is nontransferable and must be used for a ticket in the name of the person on the qualifying SkyMiles account.

Eligibility: This is a private, non-transferable offer, only intended for the recipient who receives this offer directly from Delta Air Lines by email, at an email address owned by the recipient. The recipient of the offer must book AND travel within 60 days of receiving the birthday e-mail offer using the enrollment link contained in the e-mail. This promotion ends by December 31st, 2023 (ending 11:59:59 PM, U.S. Local Time on 12/31/2023). The eCredit must be redeemed and a ticket must be issued within 180 days from receiving. There is a limit to one eCredit per eligible SkyMiles Member during the promotional period, meaning the maximum amount per SkyMiles Member will be capped at $25.

Promotion: Only flights that are marketed or operated by Delta and Delta Connection will be eligible; Delta marketed flights must be operated by one of the following carriers: Air France, AeroMexico, ITA Airways, Korean Air, KLM, China Eastern, Virgin Atlantic, West Jet, China Airlines. Travel on other carriers must be ticketed separately at applicable fare, and this Delta eCredit cannot be applied to these flights. Delta eCredits may only be used toward the total purchase price of air transportation, including taxes, fees, and surcharges imposed on the air transportation. Delta eCredits are valid on both published and unpublished fares. This Delta eCredit will not be honored when purchasing Prepaid Tickets, Award Travel, gift certificates, baggage charges, Upgrades or seat selection fees, payments on account or Delta eCerts Agency Discounts. Delta eCredits can be redeemed towards any available product cabin and no route restrictions apply. Once ticketed, penalties may apply for changes, per the fare rule purchased. The ticket must be validated on DL/006 ticket stock and the PNR (reservation number) must contain only DL-operated or marketed flights.

Promotional Reference Code: Please refer Delta customer service representative to 237502.

Promotional Fulfillment: The Delta eCredit will be added to Member’s SkyMiles account. Allow up to 7 days after qualifying in offer for credit to appear.

Miscellaneous: Offers void where prohibited by law. Other restrictions may apply. Offers and benefits are subject to change without notice. All Delta SkyMiles Program rules apply to SkyMiles Program Membership; miles, offers, mile accrual, mile redemption, and travel benefits. To review the rules, please visit delta.com/memberguide.