Section 17 of the Spam Act says a commercial message with an Australian link must clearly and accurately identify the individual or organisation who authorised it, include accurate information about how to readily contact them, and keep that information reasonably likely to be valid for at least 30 days after sending. Since 1 July 2026, texts sent under an organisation’s name at the top also need that sender ID registered.
General informationAbout the sender rules in the Spam Act 2003 and the ACMA’s SMS Sender ID Register, not legal advice about any message. The ACMA’s pages on avoiding spam and on sending texts under a business name are the places to check.
Whose message it is
Section 8 decides who authorises a message, and so whose name it must carry.
- Sent for an organisation
Where an individual authorises a message on behalf of an organisation, the organisation is taken to authorise it, and the individual is taken not to. As this guide reads it, when a salesperson sends a prospecting email for an agency, the agency is the one taken to authorise it, so the agency is who the message must identify. The salesperson who presses send still sends it, and sections 16 to 18 bind whoever sends a message or causes it to be sent.
- Sent for no one else
Where a person or organisation sends a message that nobody else authorised, the sender is taken to authorise it.
- Sent by a provider
If someone else sends messages on a business’s behalf, the ACMA says the message must still identify that business as the one that authorised it. A telco is not a sender merely because it supplies the carriage service that carries the message.
The four checks in section 17
Each check below is one paragraph of section 17(1), with the ACMA’s practical reading beside it where it gives one.
Who authorised it, clearly and accurately. The message identifies the individual or organisation who authorised its sending. The ACMA asks for the correct legal name of the business, or the person’s name and Australian Business Number.
How to reach them. It tells the recipient, accurately, how they can get in touch with that person or organisation without difficulty. The ACMA asks for “correct contact details for you or your business”.
Any conditions in the regulations. The information complies with whatever conditions the regulations set. The ACMA names the Spam Regulations alongside the Act as setting out a sender’s responsibilities.
Still true in a month. The information is reasonably likely to stay valid for at least 30 days after the message is sent. The ACMA puts it as remaining correct for at least 30 days.
Section 17 reaches further than the sender. Aiding, abetting, counselling, procuring or inducing a breach, being knowingly concerned in one, or conspiring to bring one about is also a contravention, and both the main rule and these ancillary rules are civil penalty provisions. The ACMA adds that a business cannot outsource its obligations under the spam laws: ultimately, the business is responsible.
A registered name at the top of a text
A sender ID is the branded name shown at the top of a text from a business or organisation, saying who it is from. The ACMA says businesses and organisations must register their branded sender IDs, and its page for senders says that businesses and organisations sending branded texts, small and medium businesses included, had to contact their telco or message provider to register before 1 July 2026. A sender ID that is not registered is replaced with the word “Unverified”, and texts from unverified senders are grouped in one thread on people’s phones, alongside messages that include scams. A business that sends from a phone number, or uses no sender ID, has nothing to do.
| Rule | As the ACMA sets it out |
|---|---|
| Length | At least 2 and no more than 11 characters. |
| Characters | Letters, numbers and symbols only, corresponding to decimal codes 32 to 126 of the ASCII standard; not numbers alone; no space or underscore at the start or end. Case does not matter. |
| Words | Never “Unverified”; nothing offensive, deceptive or misleading; not made up only of restricted words. |
| Link to the business | The organisation’s name or a shortened form, an acronym or initialism of it, or one of those with words about its role, location or the message’s purpose. With an ABN, it must match the registered business name, company name, trade mark or domain name. |
| Details on the ABR | To register with an ABN, the authorised contact or service of notice email address on the Australian Business Register must be up to date; the ACMA does not check Relationship Authorisation Manager arrangements for the register. |
The same sender ID can be registered by more than one organisation, if each can show a valid use for it.
The ACMA gives its reasons in terms of trust. A registered sender ID makes it harder for scammers to impersonate an organisation, and once customers know a business texts only under a certain registered name, they know to treat texts from phone numbers, or marked “Unverified”, with caution and to report them if needed. For an agency whose texts reach sellers and buyers who have never met it, that recognition is the point of the name.
A name that cannot take a reply
A branded sender name identifies the sender, but it has a limit the unsubscribe rules care about. The ACMA notes that an alphanumeric message header on an SMS is generally not capable of receiving return messages, and it has seen businesses ask people to reply to a sender ID to unsubscribe, a process it says does not work and so breaks the law. The unsubscribe guide takes that up.