This depends on the context in which the business cards were received, which usually occurs in the normal course of business and through interactions with the people you are dealing with, who expect information from you in respect of your business and vice versa. However, there a few factors you should consider when it comes to adding their details to your mailing list, which are addressed in the Spam Act 2003 (Cth) Schedule 2. This applies whether or not you have an existing business relationship with the person and whether they have provided inferred or implied consent by giving you their details via their business card. It is advisable to ask the person upfront whether they would be happy to be added to your mailing list/receive your business’s email newsletter. If you have concerns as to whether your activity breaches the Spam Act 2003 (Cth) you should seek legal advice.