Delta Airlines partners with some of the top airlines around the world, including Aeromexico, Air France and KLM Royal Dutch Airlines, as of June 2015. Delta Airlines lists all its airline partners and explains earning and redeeming reward mileage under Skymiles on its website.
As part of its frequent flier reward program, called Skymiles, Delta divides its airline partners into three tiers, which determine mileage benefits according to specific marketing criteria. For instance, as of June 2015, flights operated by Group One partner airlines allow fliers to accrue full Medallion Qualification Miles and up to 200 percent bonus miles for first or business class, whereas flights with Group 2 airlines award reduced miles and only a 100 percent bonus for higher fare classes. The Delta website contains mileage accrual information for all partner airlines.