American Express has released a promotion running through the end of the year that will give Classic, Gold and Platinum Delta SkyMiles credit cardmembers and Delta SkyMiles Business credit cardmembers a chance to earn triple SkyMiles when using their card to make Song purchases at http://www.flysong.com, as well as for all in-flight purchases. Plus, cardmembers also receive a 1,000-mile bonus for their first in-flight purchase with the card.

The offer is in tandem with, not on top of, the usual “always double miles” that cardmembers get year-round. Until Dec. 31, cardmembers will receive one extra mile in addition to the ongoing double miles feature they receive for their Delta and Song purchases.