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Trigger

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

Section titled “How it works”

The trigger is the first node in the editor.

Add Trigger to Automation

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

Add Custom Event

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

Node.js
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: [],});
PHP
$resend = Resend::client('re_xxxxxxxxx');$resend->automations->create([  'name' => 'Welcome series',  'steps' => [    [      'key' => 'start',      'type' => 'trigger',      'config' => ['event_name' => 'user.created'],    ],  ],  'connections' => [],]);
Python
import resendresend.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)
Ruby
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)
Go
package mainimport "github.com/resend/resend-go/v4"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)}
Rust
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(())}
Java
import com.resend.*;import com.resend.core.exception.ResendException;import com.resend.services.automations.model.AutomationStep;import com.resend.services.automations.model.CreateAutomationOptions;import com.resend.services.automations.model.CreateAutomationResponseSuccess;public class Main {    public static void main(String[] args) throws ResendException {        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);    }}
.NET
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
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": []}'
CLI
resend automations create --name "Welcome series" --file ./automation.json

Identifying contacts

Section titled “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:

Node.js
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',  },});
PHP
$resend = Resend::client('re_xxxxxxxxx');$resend->events->send([  'event' => 'user.created',  'contact_id' => '26e2b838-bf6d-4515-b6a7-17525b12b05a',  'payload' => ['plan' => 'pro'],]);
Python
import resendresend.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)
Ruby
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)
Go
package mainimport "github.com/resend/resend-go/v4"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",		},	})}
Rust
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(())}
Java
import com.resend.*;import com.resend.core.exception.ResendException;import com.resend.services.events.model.*;public class Main {    public static void main(String[] args) throws ResendException {        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);    }}
.NET
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
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"  }}'
CLI
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.

Node.js
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',  },});
PHP
$resend = Resend::client('re_xxxxxxxxx');$resend->events->send([  'event' => 'user.created',  'email' => 'user@example.com',  'payload' => ['plan' => 'pro'],]);
Python
import resendresend.api_key = "re_xxxxxxxxx"params: resend.Events.SendParams = {  "event": "user.created",  "email": "user@example.com",  "payload": {"plan": "pro"},}resend.Events.send(params)
Ruby
require "resend"Resend.api_key = "re_xxxxxxxxx"params = {  event: "user.created",  email: "user@example.com",  payload: { plan: "pro" },}Resend::Events.send(params)
Go
package mainimport "github.com/resend/resend-go/v4"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",		},	})}
Rust
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(())}
Java
import com.resend.*;import com.resend.core.exception.ResendException;import com.resend.services.events.model.*;public class Main {    public static void main(String[] args) throws ResendException {        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);    }}
.NET
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
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"  }}'
CLI
resend events send \
  --event user.created \
  --email user@example.com \
  --payload '{"plan":"pro"}'

Event payload

Section titled “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.

Node.js
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',  },});
PHP
$resend = Resend::client('re_xxxxxxxxx');$resend->events->send([  'event' => 'payment.failed',  'contact_id' => 'e169aa45-1ecf-4183-9955-b1499d5701d3',  'payload' => [    'amount' => 49.99,    'currency' => 'USD',    'retryDate' => '2026-11-01',  ],]);
Python
import resendresend.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)
Ruby
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)
Go
package mainimport "github.com/resend/resend-go/v4"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",		},	})}
Rust
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(())}
Java
import com.resend.*;import com.resend.core.exception.ResendException;import com.resend.services.events.model.*;public class Main {    public static void main(String[] args) throws ResendException {        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);    }}
.NET
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
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"  }}'
CLI
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

Section titled “Configuration”
  • config.event_name (string, required) — The name of the event that triggers the automation.
JSON
{
  "key": "start",
  "type": "trigger",
  "config": {
    "event_name": "user.created"
  }
}
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