In Australia a simple "No Junk Mail" sign on the mailbox makes it illegal to deliver junk mail. Mail that has gone through Australia Post that is individually addressed is legal (however now must include a way of opting out).
I imagine it might be a little different however seeing as most of the junk mail here is delivered by 15 year olds walking the block as opposed to the postal service.
In Australia a simple "No Junk Mail" sign on the mailbox makes it illegal to deliver junk mail. Mail that has gone through Australia Post that is individually addressed is legal (however now must include a way of opting out).
I imagine it might be a little different however seeing as most of the junk mail here is delivered by 15 year olds walking the block as opposed to the postal service.