Was confused so I emailed MAC.
This is what was said:
Hello Adina:
Thank you for your email. We will be happy to assist you with your order inquiry.
We sincerely apologize for any confusion that may have been caused by the backorder on your invoice or the backorder notification you received via email.
We appreciate the opportunity to clarify that the item that is listed as a backorder, Bounceback_Spring Colour_Basic, is for a promotional insert card for one of our upcoming collections. Regrettably, our stock of these insert cards ran out and caused the backorder status. Please be assured that this is a complimentary insert card that you have not been, and will not be charged for.
Once the remainder of your order has been processed and shipped, you will receive a ship confirmation with additional information.
We appreciate your patience and understanding.
HTH!