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A trigger is the first step in every Automation. It defines which event will start the Automation when received. When your application sends an event to Resend, every active Automation with a matching trigger will execute its workflow for that contact.

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How it works

The trigger is the first node in the editor.Add Trigger to AutomationChoose an existing custom event or type a new event name.Add Custom Event
Event names cannot start with the resend: prefix, which is reserved for system events.

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Identifying contacts

When sending an event to trigger an Automation, you must identify the contact using either a contact_id or an email address.
Use a contact ID when you already have the contact stored in your Audience:
import { Resend } from 'resend';

const resend = new Resend('re_xxxxxxxxx');

const { data, error } = await resend.events.send({
  event: 'user.created',
  contactId: '26e2b838-bf6d-4515-b6a7-17525b12b05a',
  payload: {
    plan: 'pro',
  },
});

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Event payload

You can include a payload object with your event to pass data into the Automation. This data becomes available as variables in subsequent steps in the Automation using the event.* namespace. 
import { Resend } from 'resend';

const resend = new Resend('re_xxxxxxxxx');

const { data, error } = await resend.events.send({
  event: 'payment.failed',
  contactId: 'e169aa45-1ecf-4183-9955-b1499d5701d3',
  payload: {
    amount: 49.99,
    currency: 'USD',
    retryDate: '2026-11-01',
  },
});
In this example, event.amount, event.currency, and event.retryDate would be available in email templates, conditions, and other steps. View the Send Event API reference for the full endpoint specification.

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Configuration

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config.event_name
string
required
The name of the event that triggers the automation.
{
  "key": "start",
  "type": "trigger",
  "config": {
    "event_name": "user.created"
  }
}