Opt-out
STOP means stop, automatically.
Honor supported stop keywords on reply-capable senders. Bird records the sender-and-subscriber suppression and exposes it to your application. Review keyword coverage and automatic replies for each country, and manage workspace-wide preferences as a separate control.
One sender. One subscriber.
Example preference
Sender and subscriber pair
Fieldnotes → Ada
Keyword suppression
Active suppression
A supported STOP blocks later messages matching this sender and subscriber.
Workspace-wide preferences and manual suppressions are separate controls.
Illustrative state changes. Country keyword coverage determines the supported behavior; this preview changes no customer preference.
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Read more customer storiesMake the opt-out path part of the integration.
Keyword handling is part of SMS sending controls on the Bird SMS platform. Configure it for the countries and reply-capable senders you use. A sender-level suppression and a workspace-wide preference have different scope; preserve that distinction when syncing your systems.
How the keywords behave.
Supported keywords, with an explicit sender and subscriber.
- 01
STOP suppresses automatically.
A supported STOP keyword opens a suppression for the sender-and-subscriber pair. Later sends matching that suppression are blocked.
- 02
HELP returns a help response.
Where the country catalogue supports it, HELP triggers the configured help response. Review the reply text and contact information for your program.
- 03
START resubscribes them.
A supported START keyword ends the corresponding keyword suppression. Manual suppressions and workspace-wide preferences have separate controls.
- 04
Query the sender-and-subscriber pair.
Inspect the suppression and workspace preferences when preparing an audience. The effective sending controls still apply when a message is submitted.
An opt-out arrives as a signed event.
When a recipient opts out, Bird suppresses them and notifies your webhook with an sms_suppression.created event so your own records stay in sync. A suppression is the exact sender and recipient pair, so the payload names the originator it stops as well as the subscriber. The event is HMAC-signed like every Bird webhook.
{
"type": "sms_suppression.created",
"timestamp": "2026-05-19T15:42:01.221Z",
"data": {
"suppression_id": "ssu_01krdgeqcxet5s7t44vh8rt9mg",
"workspace_id": "ws_01krdgeqcxet5s7t44vh8rt9mg",
"destination": "+15005550006",
"originator": "+12025550188",
"reason": "keyword_stop"
}
}
Opt-out is an inbound flow.
Supported keywords arrive through two-way SMS. Bird evaluates the reply, updates the relevant suppression and still exposes the inbound event. Use those events to keep your application informed without replacing the sending controls.
Questions about registration and sending
Can a recipient resume receiving messages?
How do I check suppression before sending?
Put it into practice.
Continue with the documentation, guides and examples for this topic. Resources are in English.
Other compliance topics
Opt-out is one of three SMS compliance regimes. See the rest.
Keep the customer’s preference connected.
Read keyword coverage, configure replies and sync sender-and-subscriber suppressions. Keep workspace-wide preferences in view when preparing the next campaign.