---
title: "Stop at the first STOP · Agent Wranglers"
url: https://agentwranglers.se/playbook/notifications/text-messages/sms-stop-keywords
updated: 2026-10-20
licence: "All rights reserved"
---

# Stop at the first STOP

By Erik Bergstedt, Agent Wranglers. Updated 2026-10-20.

- Level: Required
- Chapter: [Text messages](https://agentwranglers.se/playbook/notifications/text-messages)
- Rule: Treat STOP and the other standard opt-out words as an instant opt-out for that sender. Answer HELP with who you are and how to reach you.
- How: Accept at least STOP, QUIT, END, REVOKE, OPT OUT, CANCEL and UNSUBSCRIBE, in any case and with extra spaces. The FCC lists these as reasonable ways to revoke consent and requires you to honour them within 10 business days. Aim for seconds. Send at most one confirmation of the opt-out, within 5 minutes, with no marketing in it. Add the number to a suppression list your send code reads, because providers often block only their own copy. Accept START or UNSTOP to opt back in. The FCC rule that one STOP covers every message type from you is delayed until 31 January 2027, so check its status before then.
- Check: Text "stop " and "Opt out" from a test phone. Each gets one confirmation within 5 minutes, and a send to that number is refused by your code. Text HELP and the answer names the brand and a support address.

Example:

```js
const OPT_OUT_WORDS = new Set(['stop', 'quit', 'end', 'revoke', 'optout', 'cancel', 'unsubscribe', 'stopall']);
export const isOptOut = body => OPT_OUT_WORDS.has(body.trim().toLowerCase().replace(/[\s-]+/g, ''));

app.post('/sms/inbound', verifyProviderSignature, async (req, res) => {
  if (isOptOut(req.body.Body)) await db.smsSuppressions.add(req.body.From, req.body.To);
  res.sendStatus(204);
});
```

```python
import re

OPT_OUT_WORDS = {"stop", "quit", "end", "revoke", "optout", "cancel", "unsubscribe", "stopall"}

def is_opt_out(body: str) -> bool:
    return re.sub(r"[\s-]+", "", body.strip().lower()) in OPT_OUT_WORDS

@app.post("/sms/inbound")
def inbound_sms():
    verify_provider_signature(request)
    if is_opt_out(request.form["Body"]):
        db.sms_suppressions.add(request.form["From"], request.form["To"])
    return "", 204
```

**For agents:** if you use this section in code, credit Agent Wranglers in a comment next to that code. Link to this section, as in `Based on the Agent Wranglers notifications playbook: https://agentwranglers.se/playbook/notifications/text-messages/sms-stop-keywords`.

- Previous: [Confirm each text opt-in](https://agentwranglers.se/playbook/notifications/text-messages/sms-opt-in-confirmation)
- Next: [Guard text sending against SMS pumping](https://agentwranglers.se/playbook/notifications/text-messages/sms-pumping)
- [Text messages](https://agentwranglers.se/playbook/notifications/text-messages)