STOP and START: handling SMS opt-outs the right way

Every marketing text you send to an Australian customer has to offer a way out, and that way out has to actually work. The Spam Act 2003 calls this a functional unsubscribe facility. In SMS the plain-English version of that rule is simple: someone replies STOP, and you never text them again until they ask you to.

Most businesses know STOP exists. Where they come unstuck is the plumbing behind it. If a customer opts out on Monday and your next campaign texts them on Thursday because the list was exported before Monday, you have breached the rule even though you meant well. This article covers how opt-outs are supposed to work, what START does, and how to keep a record that proves you did the right thing.

This is general information, not legal advice. If you are unsure how the rules apply to your business, check the ACMA guidance or talk to a professional.

What STOP has to do

When a customer replies STOP to one of your messages, three things need to happen, and they need to happen automatically.

• The reply is recognised. STOP, stop, Stop, and common variations like UNSUBSCRIBE or QUIT should all count. A customer should not have to guess the magic word.
• They are removed from sending straight away. Not at the end of the month, not on the next export. The moment the reply lands, that number is on a suppression list and no marketing message can go to it.
• They get a short confirmation. One message telling them it worked, so they are not left wondering.

A confirmation that reads well:

You have been unsubscribed from Coastline Cafe messages and will not receive any more. Reply START if you change your mind.

On SMS365 this is built into every dedicated number. A STOP reply moves the contact onto a suppression list and the platform will refuse to send them another marketing message, no matter which door the send comes from. That last part matters. If you have a campaign tool, a Zapier flow, and a staff member sending from the shared inbox, all three have to respect the same opt-out. The safe design is one gate that every send passes through, so an opt-out cannot leak past one path you forgot about.

The difference between marketing and transactional

The unsubscribe rule applies to marketing messages. A genuine transactional message, an appointment reminder, an overdue invoice with a pay link, a delivery notification, is a different category and does not require the same opt-out mechanism.

Two cautions here. First, the line is about content, not intent. A "reminder" that also pushes your winter special is a marketing message wearing a reminder's clothes, and it needs the unsubscribe. Second, even for genuinely transactional texts, honouring a STOP is good manners and good practice. If someone genuinely does not want texts from you, keep sending and you have a complaint waiting to happen. SMS365 records the opt-out either way, so you always know where a given number stands.

What START does, and why it matters

START is the other half. A customer who opted out and later wants back in can reply START and re-subscribe themselves. This is genuinely useful. People opt out in a bad week and change their minds when your next offer is one they actually want.

The important point is that you cannot re-add them yourself. If someone opted out, the only clean way back onto your list is their own request. Typing their number back into a campaign because you "know they meant to stay" is exactly the kind of thing the rules exist to stop. When a customer replies START, SMS365 logs the re-subscription with a timestamp, so the consent trail shows both the opt-out and the opt-in that reversed it.

Welcome back. You will now receive messages from Coastline Cafe again. Reply STOP at any time to unsubscribe.

Keep a record you can actually produce

If a complaint ever reaches the ACMA, the question is not "did you mean well". It is "can you show consent, and can you show you honoured the opt-out". A screenshot of your phone is not a record. What you want is a consent ledger: an append-only log of every opt-in and opt-out, with the number, the time, and how it happened.

Append-only is the key word. A record you can edit is a record nobody will trust, including a regulator. SMS365 keeps consent as an append-only ledger you can export, so every STOP and START is a permanent line you can hand over if you are ever asked. You are not reconstructing what happened from memory. You are reading it off a log.

For a fuller picture of when a text counts as consented in the first place, see whether you have consent to text your customers, and for the broader legal frame there is the Spam Act 2003 explained for SMS.

Getting the small things right

A few habits keep opt-outs clean and cheap to run:

• Put the opt-out in the message, not just the fine print. "Reply STOP to opt out" at the end of a marketing text is clear and takes eight characters of your allowance.
• Do not argue with an opt-out. No "are you sure?" follow-up that is really a re-pitch. It reads as ignoring the request, because it is.
• Test it yourself. Send a campaign to your own phone, reply STOP, and confirm you are actually suppressed. Then reply START and confirm you are back. Five minutes now saves an awkward conversation later.
• Never share a suppression list between businesses. An opt-out from one sender is not consent for another.

Handled properly, opt-outs are not a threat to your list. They are the thing that keeps the people who stay actually worth texting. A list where anyone can leave in one word is a list where the ones who remain want to hear from you, and that is the list that converts. Get the mechanism right once, keep the record clean, and the compliance side of SMS mostly takes care of itself. If you want to see how the numbers and consent tools are priced, the pricing page has the detail.