Hi guys,
I thought it might be worth posting an additional AMA from a different sector of Australia Post after I saw tsu-chan's AMA.
I deal with customer operations and have a lot of experiencing interacting with all parts of the company. Ask me absolutely anything and I'll do my best to explain or answer it.
Side note; if you think it's best I attempt to post replies to the other AMA, let me know.
EDIT: On that Monday to Friday grind, I'll answer everything tonight
All standard parcel post are transported via ground services. We use both trains and trucks to have items transported from the East Coast to the west. Express post is an air-mail service within almost every area.
Letters themselves use a mix of both ground and air services, depend on location and expected transit times.