Through Aug. 15, SkyMiles members can earn 2,500 bonus miles when they refer five people to the SkyMiles program — 500 miles for each referral. When the referred member activates their account by flying with Delta or by earning miles with any of Delta’s partners through Dec. 15, they will receive a 1,000-mile bonus. Visit http://www.delta.com/referrals to enter five referral email addresses.