If you are sending documents in something that is not a Magic Envelope, all you need to do is address it to Squirrel Street and include a coversheet with your first and last name and email address.
Or you can print off a coversheet from within the account. Here are links to instructions on how to find a ready-made cover sheet for your account.
For Australia and NZ Mail:
PO Box 1333
Crows Nest NSW 1585
If you mail in your documents by courier, fees and charges may apply to couriers other than Australia Post and StarTrack to deliver parcels to PO Boxes. Couriers may pass this cost on to customers.
If you need to hand deliver anything, you'll need to deliver it to Crows Nest Post Office (NSW). Please note that there is a surcharge for delivering mail by hand to a PO Box.