Amplify has re-imagined the way frontend developers build fullstack applications. Develop and deploy without the hassle.

Page updated Apr 24, 2024

Custom message

You can use defineAuth and defineFunction to create an Amazon Cognito custom message AWS Lambda trigger thats sends an custom email or phone verification message, or a multi-factor authentication (MFA) code.

To get started, install @types/aws-lambda package that will be used to define the type of the handler:

npm add --save-dev @types/aws-lambda

Next, create a new directory and a resource file, amplify/auth/custom-message/resource.ts. Then, define the function with defineFunction:

import { defineFunction } from '@aws-amplify/backend';
export const customMessage = defineFunction({
name: "custom-message",

Next, create the corresponding handler file, amplify/auth/custom-message/handler.ts, file with the following contents:

import type { CustomMessageTriggerHandler } from "aws-lambda";
export const handler: CustomMessageTriggerHandler = async (event) => {
if (event.triggerSource === "CustomMessage_ForgotPassword") {
const locale = event.request.userAttributes["locale"];
if (locale === "en") {
event.response.emailMessage = `Your new one-time code is ${event.request.codeParameter}`;
event.response.emailSubject = "Reset my password";
} else if (locale === "es") {
event.response.emailMessage = `Tu nuevo código de un solo uso es ${event.request.codeParameter}`;
event.response.emailSubject = "Restablecer mi contraseña";
return event;

Lastly, set the newly created function resource on your auth resource:

import { defineAuth } from '@aws-amplify/backend';
import { customMessage } from "./custom-message/resource";
export const auth = defineAuth({
// ...
triggers: {

After deploying the changes, whenever a user with user attribute locale set to es attempts to reset a password they will receive an email with a one-time code in Spanish.