It's important to understand the rules, as Australian businesses face fines of up to $1.1 million a day for repeat corporate offenders. Australia's 2003 Spam Act doesn't just apply to emails, it also applied to SMS and MMS messages of a business nature.
There are three basic steps you should follow to ensure you stay on the right side of Australia's anti-spam laws; Consent, Identify and Unsubscribe.
You should only send commercial electronic messages to people with their expressed or inferred consent. Inferred consent can be a grey area, but it generally revolves around having an ongoing existing relationship with someone who has previously provided their contact details.
Should a complaint be made the Australian Communications and Media Authority will be the judge of inferred consent, but its guidelines suggest a one-off purchase such as a "t-shirt or groceries from a shop, attendance at a concert, performance or movie" would not be a good basis for inferring consent.
Identify is more straightforward. Your message must include clear and accurate information about the person or business responsible for sending the message. Identification details must be reasonably likely to be accurate for at least the next 30 days.
Unsubscribe details are also important and this is the area which often trips up businesses. Even short text messages are expected to offer some form of unsubscribe facility, allowing people to indicate they no longer want to receive such messages. Unsubscribe requests must be honoured within five working days. Similar to identification details, the unsubscribe details are expected to be valid for at least 30 days.
Stick to these guidelines and you should stay on the right side of Australia's spam laws. For more details you can visit ACMA's Spam Act and Codes of Practice page.