Profile: Bovver Boy
The only good Redback around your yard is a dead Redback...
The preferred method of removing that little rascal from your letterbox is to squish it on the end of a blunt stick, or using a pair of thick and tough gloves, (i.e. gardening, riggers, or welding gloves..).
Just make sure you squash them before they bite you - after being bitten once (by one under a beehive's bottom-board..), I don't give them another chance these days.