MyPost Carrier Printer Settings
Go to Settings ⇒ Carriers and click the blue cog to access the Printer Setup Page.
Basic Printer Settings
On this page you can view the selections for the label types, Standard/Express/international, each with set limitations of number per page depending on the label type.
If you intend to use a thermal printer, you need to set them to A6 - 1 per Page.
Note: It is a known issue with Auspost that international labels cannot be printed on an A6 label and they are reviewing their systems.