Delta’s new bonus mile offer for partner activity is called Pile on Miles. Registration required.
Partner activity through June 22 counts towards incrementally more bonus miles, and each partner can only count once for the offer.
Unique Partner Activities
4 ———– 4,000 miles
6 ———– 6,000 miles
8 ———– 8,000 miles
15 ———– 15,000 miles
25 ———– 25,000 miles
Northwest is making the same offer, which means that between the two programs 50 partner activities earn up to 50,000 bonus miles.