Postscript

Postscript is an SMS marketing platform for ecommerce brands. Datafly Signal delivers your events server-side to Postscript’s Custom Events API, where they trigger Flows (automations) such as abandoned-cart, browse-abandonment, and post-purchase journeys. Because delivery is server-to-server, events reach Postscript even when a browser blocks third-party scripts.

Prerequisites

• A Postscript account with SMS subscribers.
• A Postscript Private API Key (sk_...). Generate it in the Postscript dashboard under Account > API (app.postscript.io/account/api). Use the Private key, never the Public key, and never expose it in client-side code.
• At least one of phone, email, or a Postscript subscriber ID flowing through your Signal events so Postscript can resolve the subscriber.

Configuration

In your Postscript dashboard:

1. Go to Account > API.
2. Copy the Private API Key (sk_...).

Configure in Signal

1. In the Signal management UI, open Integrations and add Postscript.
2. Paste your Private API Key into the API Key field.
3. Attach the Postscript integration to the pipeline that carries the events you want to trigger Flows.
4. Save and publish. New events on that pipeline now deliver to Postscript.

API Endpoint

Signal delivers events to Postscript’s Custom Events API:

POST https://api.postscript.io/api/v2/events
Authorization: Bearer <Private API Key>
Content-Type: application/json

A successful request returns 202 Accepted. The event name (type) is automatically prefixed with your shop name in Postscript, so an order_completed event appears in Flows as [Your Shop] - order_completed.

Identity Signals

Postscript resolves the subscriber from one or more identifiers on each event. Unlike ad-platform conversion APIs, Postscript matches on the raw value, not a hash:

If none of these are present, Postscript cannot attach the event to a subscriber and the request is rejected. Make sure your identity setup surfaces at least a phone or email for converting visitors.

Event Mapping

Signal uses GA4-style event names. The default Postscript blueprint maps them as follows:

Any event not in the map is dropped. Event-specific fields land inside the properties object, where they are available for Flow filtering and SMS merge tags (for example {{ event.properties.order_id }}).

Example: Order Completed

A Datafly.js call:

datafly.track("Order Completed", {
  order_id: "1001",
  revenue: 79.99,
  currency: "USD",
  tax: 6.40,
  shipping: 5.00,
  coupon: "WELCOME10"
});

With a subscriber phone of +15551234567, Signal delivers:

{
  "type": "order_completed",
  "phone": "+15551234567",
  "occurred_at": "2026-06-06 14:32:11.482000",
  "external_id": "evt_9f2c1b7e",
  "properties": {
    "order_id": "1001",
    "value": 79.99,
    "currency": "USD",
    "tax": 6.40,
    "shipping": 5.00,
    "coupon": "WELCOME10"
  }
}

external_id is sourced from the Signal event’s message ID so retried deliveries are idempotent. occurred_at is the event timestamp in UTC.

Testing

1. Send a test event through your pipeline (for example, complete a test order) for a visitor whose phone or email matches an existing Postscript subscriber.
2. In Postscript, open the subscriber’s profile or Flows activity and confirm the event appears as [Your Shop] - order_completed.
3. Build or edit a Flow triggered by the custom event and confirm the properties values resolve in merge tags.

Troubleshooting

• 400 Bad Request — the event had no resolvable subscriber identifier (no phone, email, or subscriber_id), or type contained characters other than letters, numbers, and underscores. Confirm identity is flowing and the event maps to a valid type.
• 401 / 403 Unauthorized — the Private API Key is wrong, revoked, or you pasted the Public key. Regenerate the Private key in Account > API and update the integration.
• Event not triggering a Flow — confirm the Flow trigger matches the prefixed event name ([Your Shop] - <type>) and that the subscriber is opted in to SMS. Postscript only sends to subscribers who have consented; the event API does not override SMS consent state.
• Subscriber not matched — verify the phone is in E.164 (+ and country code). Postscript matches on the raw value, so formatting differences can prevent a match.