as written in the email:
Book an eligible Economy international Qantas or Jetstar Classic Flight Reward* between 16 December and 11.59pm (AEDT) 22 December 2015. Your discount will be automatically applied to the points required. Taxes, fees and carrier charges payable in addition to points required.
Travel on Qantas between 13 January and 2 December 2016 or travel on Jetstar between 13 January and 30 September 2016.
I have been looking at booking flights to hawaii, and can see that the cost has been discounted. :)
ridiculous tax charges for the award tickets.