Trigger - Resend

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.

How it works

Using the dashboard
Using the API

The trigger is the first node in the editor.

Choose an existing custom event or type a new event name.

When creating an Automation via the API, the trigger is defined as the first item in the steps array with type: 'trigger'.

import { Resend } from 'resend';

const resend = new Resend('re_xxxxxxxxx');

const { data, error } = await resend.automations.create({
  name: 'Welcome series',
  steps: [
    {
      key: 'start',
      type: 'trigger',
      config: { eventName: 'user.created' },
    },
  ],
  connections: [],
});

$resend = Resend::client('re_xxxxxxxxx');

$resend->automations->create([
  'name' => 'Welcome series',
  'steps' => [
    [
      'key' => 'start',
      'type' => 'trigger',
      'config' => ['event_name' => 'user.created'],
    ],
  ],
  'connections' => [],
]);

import resend

resend.api_key = "re_xxxxxxxxx"

params: resend.Automations.CreateParams = {
  "name": "Welcome series",
  "steps": [
    {
      "key": "start",
      "type": "trigger",
      "config": {"event_name": "user.created"},
    },
  ],
  "connections": [],
}

resend.Automations.create(params)

require "resend"

Resend.api_key = "re_xxxxxxxxx"

params = {
  name: "Welcome series",
  steps: [
    {
      key: "start",
      type: "trigger",
      config: { event_name: "user.created" },
    },
  ],
  connections: [],
}

Resend::Automations.create(params)

package main

import "github.com/resend/resend-go/v3"

func main() {
	client := resend.NewClient("re_xxxxxxxxx")

	params := &resend.CreateAutomationRequest{
		Name: "Welcome series",
		Steps: []resend.AutomationStep{
			{
				Key:  "start",
				Type: resend.AutomationStepTypeTrigger,
				Config: map[string]any{
					"event_name": "user.created",
				},
			},
		},
		Connections: []resend.AutomationConnection{},
	}

	client.Automations.Create(params)
}

use resend_rs::{
  types::{AutomationStatus, CreateAutomationOptions, Step, TriggerStepConfig},
  Resend, Result,
};

#[tokio::main]
async fn main() -> Result<()> {
  let resend = Resend::new("re_xxxxxxxxx");

  let opts = CreateAutomationOptions {
    name: "Welcome series".to_owned(),
    steps: vec![Step::Trigger {
      key: "start".to_owned(),
      config: TriggerStepConfig {
        event_name: "user.created".to_owned(),
      },
    }],
    connections: vec![],
    status: AutomationStatus::Disabled,
  };
  let _automation = resend.automations.create(opts).await?;

  Ok(())
}

import com.resend.*;

public class Main {
    public static void main(String[] args) {
        Resend resend = new Resend("re_xxxxxxxxx");

        CreateAutomationOptions options = CreateAutomationOptions.builder()
                .name("Welcome series")
                .steps(
                    AutomationStep.trigger("start")
                        .eventName("user.created")
                        .build()
                )
                .build();

        CreateAutomationResponseSuccess data = resend.automations().create(options);
    }
}

using Resend;
using System.Text.Json;

IResend resend = ResendClient.Create( "re_xxxxxxxxx" );

var startConfig = JsonSerializer.SerializeToElement( new { event_name = "user.created" } );

var resp = await resend.AutomationCreateAsync( new AutomationCreateData()
{
    Name = "Welcome series",
    Steps = new List<AutomationStepData>
    {
        new AutomationStepData { Ref = "start", Type = "trigger", Config = startConfig },
    },
    Connections = new List<AutomationEdge>(),
} );

curl -X POST 'https://api.resend.com/automations' \
     -H 'Authorization: Bearer re_xxxxxxxxx' \
     -H 'Content-Type: application/json' \
     -d '{
  "name": "Welcome series",
  "steps": [{
    "key": "start",
    "type": "trigger",
    "config": { "event_name": "user.created" }
  }],
  "connections": []
}'

resend automations create --name "Welcome series" --file ./automation.json

Event names cannot start with the resend: prefix, which is reserved for system events.

Identifying contacts

When sending an event to trigger an Automation, you must identify the contact using either a contact_id or an email address.

Using contact ID
Using 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',
  },
});

$resend = Resend::client('re_xxxxxxxxx');

$resend->events->send([
  'event' => 'user.created',
  'contact_id' => '26e2b838-bf6d-4515-b6a7-17525b12b05a',
  'payload' => ['plan' => 'pro'],
]);

import resend

resend.api_key = "re_xxxxxxxxx"

params: resend.Events.SendParams = {
  "event": "user.created",
  "contact_id": "26e2b838-bf6d-4515-b6a7-17525b12b05a",
  "payload": {"plan": "pro"},
}

resend.Events.send(params)

require "resend"

Resend.api_key = "re_xxxxxxxxx"

params = {
  event: "user.created",
  contact_id: "26e2b838-bf6d-4515-b6a7-17525b12b05a",
  payload: { plan: "pro" },
}

Resend::Events.send(params)

package main

import "github.com/resend/resend-go/v3"

func main() {
	client := resend.NewClient("re_xxxxxxxxx")

	client.Events.Send(&resend.SendEventRequest{
		Event:     "user.created",
		ContactId: "26e2b838-bf6d-4515-b6a7-17525b12b05a",
		Payload: map[string]any{
			"plan": "pro",
		},
	})
}

use resend_rs::{
  json,
  types::{ContactIdOrEmail, SendEventOptions},
  Resend, Result,
};

#[tokio::main]
async fn main() -> Result<()> {
  let resend = Resend::new("re_xxxxxxxxx");

  let _event = resend
    .events
    .send(SendEventOptions {
      event: "user.created".to_owned(),
      contact_id_or_email: ContactIdOrEmail::ContactId(
        "26e2b838-bf6d-4515-b6a7-17525b12b05a".to_owned(),
      ),
      payload: json!({ "plan": "pro" }),
    })
    .await?;

  Ok(())
}

import com.resend.*;
import com.resend.services.events.model.*;

public class Main {
    public static void main(String[] args) {
        Resend resend = new Resend("re_xxxxxxxxx");

        SendEventOptions params = SendEventOptions.builder()
                .event("user.created")
                .contactId("26e2b838-bf6d-4515-b6a7-17525b12b05a")
                .addPayload("plan", "pro")
                .build();

        SendEventResponseSuccess data = resend.events().send(params);
    }
}

using Resend;
using System.Text.Json;

IResend resend = ResendClient.Create( "re_xxxxxxxxx" );

var payload = JsonSerializer.SerializeToElement( new { plan = "pro" } );

var resp = await resend.EventSendAsync( new EventSendData()
{
    Event = "user.created",
    ContactId = new Guid( "26e2b838-bf6d-4515-b6a7-17525b12b05a" ),
    Payload = payload,
} );

curl -X POST 'https://api.resend.com/events/send' \
     -H 'Authorization: Bearer re_xxxxxxxxx' \
     -H 'Content-Type: application/json' \
     -d '{
  "event": "user.created",
  "contact_id": "26e2b838-bf6d-4515-b6a7-17525b12b05a",
  "payload": {
    "plan": "pro"
  }
}'

resend events send \
  --event user.created \
  --contact-id 26e2b838-bf6d-4515-b6a7-17525b12b05a \
  --payload '{"plan":"pro"}'

Use an email address to trigger the Automation. If no contact with the provided email exists in your Audience, Resend will automatically create one when the run starts.

import { Resend } from 'resend';

const resend = new Resend('re_xxxxxxxxx');

const { data, error } = await resend.events.send({
  event: 'user.created',
  email: 'user@example.com',
  payload: {
    plan: 'pro',
  },
});

$resend = Resend::client('re_xxxxxxxxx');

$resend->events->send([
  'event' => 'user.created',
  'email' => 'user@example.com',
  'payload' => ['plan' => 'pro'],
]);

import resend

resend.api_key = "re_xxxxxxxxx"

params: resend.Events.SendParams = {
  "event": "user.created",
  "email": "user@example.com",
  "payload": {"plan": "pro"},
}

resend.Events.send(params)

require "resend"

Resend.api_key = "re_xxxxxxxxx"

params = {
  event: "user.created",
  email: "user@example.com",
  payload: { plan: "pro" },
}

Resend::Events.send(params)

package main

import "github.com/resend/resend-go/v3"

func main() {
	client := resend.NewClient("re_xxxxxxxxx")

	client.Events.Send(&resend.SendEventRequest{
		Event: "user.created",
		Email: "user@example.com",
		Payload: map[string]any{
			"plan": "pro",
		},
	})
}

use resend_rs::{
  json,
  types::{ContactIdOrEmail, SendEventOptions},
  Resend, Result,
};

#[tokio::main]
async fn main() -> Result<()> {
  let resend = Resend::new("re_xxxxxxxxx");

  let _event = resend
    .events
    .send(SendEventOptions {
      event: "user.created".to_owned(),
      contact_id_or_email: ContactIdOrEmail::Email("user@example.com".to_owned()),
      payload: json!({ "plan": "pro" }),
    })
    .await?;

  Ok(())
}

import com.resend.*;
import com.resend.services.events.model.*;

public class Main {
    public static void main(String[] args) {
        Resend resend = new Resend("re_xxxxxxxxx");

        SendEventOptions params = SendEventOptions.builder()
                .event("user.created")
                .email("user@example.com")
                .addPayload("plan", "pro")
                .build();

        SendEventResponseSuccess data = resend.events().send(params);
    }
}

using Resend;
using System.Text.Json;

IResend resend = ResendClient.Create( "re_xxxxxxxxx" );

var payload = JsonSerializer.SerializeToElement( new { plan = "pro" } );

var resp = await resend.EventSendAsync( new EventSendData()
{
    Event = "user.created",
    Email = "user@example.com",
    Payload = payload,
} );

curl -X POST 'https://api.resend.com/events/send' \
     -H 'Authorization: Bearer re_xxxxxxxxx' \
     -H 'Content-Type: application/json' \
     -d '{
  "event": "user.created",
  "email": "user@example.com",
  "payload": {
    "plan": "pro"
  }
}'

resend events send \
  --event user.created \
  --email user@example.com \
  --payload '{"plan":"pro"}'

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',
  },
});

$resend = Resend::client('re_xxxxxxxxx');

$resend->events->send([
  'event' => 'payment.failed',
  'contact_id' => 'e169aa45-1ecf-4183-9955-b1499d5701d3',
  'payload' => [
    'amount' => 49.99,
    'currency' => 'USD',
    'retryDate' => '2026-11-01',
  ],
]);

import resend

resend.api_key = "re_xxxxxxxxx"

params: resend.Events.SendParams = {
  "event": "payment.failed",
  "contact_id": "e169aa45-1ecf-4183-9955-b1499d5701d3",
  "payload": {
    "amount": 49.99,
    "currency": "USD",
    "retryDate": "2026-11-01",
  },
}

resend.Events.send(params)

require "resend"

Resend.api_key = "re_xxxxxxxxx"

params = {
  event: "payment.failed",
  contact_id: "e169aa45-1ecf-4183-9955-b1499d5701d3",
  payload: {
    amount: 49.99,
    currency: "USD",
    retryDate: "2026-11-01",
  },
}

Resend::Events.send(params)

package main

import "github.com/resend/resend-go/v3"

func main() {
	client := resend.NewClient("re_xxxxxxxxx")

	client.Events.Send(&resend.SendEventRequest{
		Event:     "payment.failed",
		ContactId: "e169aa45-1ecf-4183-9955-b1499d5701d3",
		Payload: map[string]any{
			"amount":    49.99,
			"currency":  "USD",
			"retryDate": "2026-11-01",
		},
	})
}

use resend_rs::{
  json,
  types::{ContactIdOrEmail, SendEventOptions},
  Resend, Result,
};

#[tokio::main]
async fn main() -> Result<()> {
  let resend = Resend::new("re_xxxxxxxxx");

  let _event = resend
    .events
    .send(SendEventOptions {
      event: "payment.failed".to_owned(),
      contact_id_or_email: ContactIdOrEmail::ContactId(
        "e169aa45-1ecf-4183-9955-b1499d5701d3".to_owned(),
      ),
      payload: json!({
        "amount": 49.99,
        "currency": "USD",
        "retryDate": "2026-11-01"
      }),
    })
    .await?;

  Ok(())
}

import com.resend.*;
import com.resend.services.events.model.*;

public class Main {
    public static void main(String[] args) {
        Resend resend = new Resend("re_xxxxxxxxx");

        SendEventOptions params = SendEventOptions.builder()
                .event("payment.failed")
                .contactId("e169aa45-1ecf-4183-9955-b1499d5701d3")
                .addPayload("amount", 49.99)
                .addPayload("currency", "USD")
                .addPayload("retryDate", "2026-11-01")
                .build();

        SendEventResponseSuccess data = resend.events().send(params);
    }
}

using Resend;
using System.Text.Json;

IResend resend = ResendClient.Create( "re_xxxxxxxxx" );

var payload = JsonSerializer.SerializeToElement( new
{
    amount = 49.99,
    currency = "USD",
    retryDate = "2026-11-01",
} );

var resp = await resend.EventSendAsync( new EventSendData()
{
    Event = "payment.failed",
    ContactId = new Guid( "e169aa45-1ecf-4183-9955-b1499d5701d3" ),
    Payload = payload,
} );

curl -X POST 'https://api.resend.com/events/send' \
     -H 'Authorization: Bearer re_xxxxxxxxx' \
     -H 'Content-Type: application/json' \
     -d '{
  "event": "payment.failed",
  "contact_id": "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx",
  "payload": {
    "amount": 49.99,
    "currency": "USD",
    "retryDate": "2026-11-01"
  }
}'

resend events send \
  --event payment.failed \
  --contact-id e169aa45-1ecf-4183-9955-b1499d5701d3 \
  --payload '{"amount":49.99,"currency":"USD","retryDate":"2026-11-01"}'

In this example, you can use event.amount, event.currency, and event.retryDate in other automation conditions and steps, or in email templates. View the Send Event API reference for the full endpoint specification.

Configuration

config.event_name

string

required

The name of the event that triggers the automation.

{
  "key": "start",
  "type": "trigger",
  "config": {
    "event_name": "user.created"
  }
}

​How it works

​Identifying contacts

​Event payload

​Configuration

How it works

Identifying contacts

Event payload

Configuration