I received the email last month.
Dear lidotaja,
In celebration of your birthday this February, enjoy double A+ Rewards credits on your next AirTran Airways flight. To earn double A+ Rewards credits simply:
Go to AirTran.com between February 1, 2013, and February 28, 2013,
and book your AirTran flight for travel by April 30, 2013.
Enjoy the flight! Once you complete your travel, double A+ Rewards credits will be posted to your account within 8-10 weeks.