Originally Posted by
SuperG1955
You don't have to book through the AMEX Travel portal . You just have to charge it to the AMEX Platinum/Centurion card.
I've booked directly with DL, AM, KL, IB, and AZ and always gotten the 5X MR points.
One caveat - I don't know what happens when you book it through an OTA since I've never done that,
That applies only for a personal card. Business Platinum cards require use of the Amex portal.