Unfortunately, only flights booked between April 15 and July 15, 2012 will be eligible for this promotion. Hence, if you have multiple flights that were ticketed before April 15th, you're out of luck unless you can cancel and rebook them. Travel must take place between April 15 and July 15, 2012, excluding July 3 through July 5, 2012. Bonus miles do not count towards Premier status, and will be credited 6-8 weeks after the promotion end date on July 15, 2012. You must register prior to travel.
For those of you who were not targeted and did not receive an email, you can still try to register for this promotion by following this link. Enter your MileagePlus membership number and see what your personalized offer is. Some people got a message saying they are not eligible at all, while others have reported a myriad of roundtrip thresholds, including 1/2/4, 1/2/5, 2/4/6, 5/6/7, 6/7/8, 7/8/9, and even 8/9/10! Obviously, this promotion only makes sense up to a certain number of roundtrip flights. If you were lucky enough to get one of the lower thresholds, it might be worth the effort, especially if you already have travel plans.