In Australia, mass email marketing and spam is covered under a Commonwealth act known as the Spam Act 2003. The act in a nutshell tells marketers (or anyone sending an email) their electronic messages (yes, it also covers SMS):

• Unsolicited commercial electronic messages must not be sent unless it is a designated commercial electronic message defined at Schedule 1 of the act.
• Commercial electronic messages must include information about the individual or organisation who authorised the sending of the message.
• Commercial electronic messages must contain a functional unsubscribe facility.
• Address‑harvesting software must not be supplied, acquired or used.
• An electronic address list produced using address‑harvesting software must not be supplied, acquired or used.

The Spam Act 2003 is enforced by the Australian Communications and Media Authority. If you send an unsolicited message - that is, if someone does not opt-in to your marketing electronically - they are well within their rights to complain to the ACMA. Your first offence will be a polite cease and desist, and the next offences will be met with fines and lawsuits. That means if someone hands you a business card, it does NOT entitle you to add them to your marketing lists. You require an electronic confirmation from anyone who wishes to opt-in. (This is a pet peeve of mine - and if you do it, you could be in a lot of hot water!)