Beginner

Serverless Contact Form

Build a contact form that sends emails using API Gateway, Lambda, and SES

Project Overview

Create a fully serverless contact form that processes submissions and sends email notifications. No servers to manage, and you only pay for what you use.

Difficulty: Beginner

AWS Services: API Gateway, Lambda, SES, DynamoDB

Cost: Free Tier eligible

Prerequisites

AWS account (Free Tier)
Basic JavaScript/Python knowledge
A verified email address for SES
HTML form on your website

Architecture

📄

Web Form

Frontend

→

🔗

API Gateway

REST API

→

⚡

Lambda

Process Form

→

✉

SES

Send Email

Optional: Store submissions in DynamoDB for backup

Step-by-Step Instructions

Verify Email in SES

Go to Amazon SES in the AWS Console
Click "Verified identities" then "Create identity"
Choose "Email address" and enter your email
Check your inbox and click the verification link
Note: In sandbox mode, both sender and recipient must be verified

Create the Lambda Function

Go to Lambda and click "Create function"
Choose "Author from scratch"
Name it "ContactFormHandler"
Select Python 3.12 or Node.js 20.x runtime
Create a new execution role with basic Lambda permissions

Add Lambda Code

Parse the incoming JSON body (name, email, message)
Validate required fields
Use boto3 (Python) or AWS SDK to send email via SES
Return appropriate response with CORS headers
Add error handling for failed sends

Set Up API Gateway

Go to API Gateway and create a REST API
Create a new resource called "/contact"
Add a POST method
Connect it to your Lambda function
Enable Lambda Proxy integration

Configure CORS

Select the /contact resource
Click "Enable CORS" from the Actions menu
Set allowed origin to your website domain
Enable for POST and OPTIONS methods
Deploy the API to a stage (e.g., "prod")

Connect Your Frontend

Copy the API Gateway invoke URL
Update your HTML form to submit via fetch/AJAX
Send POST request with JSON body
Handle success and error responses
Test the complete flow

Tips

Use environment variables for email addresses - Don't hardcode emails in your Lambda code
Add input validation - Sanitize inputs to prevent injection attacks
Request SES production access - Submit a request to send to any email address
Add rate limiting - Use API Gateway throttling to prevent abuse

Code Examples

Lambda Function (Python)

lambda_function.py PYTHON

import json
import boto3
import os

ses = boto3.client('ses')

def lambda_handler(event, context):
    try:
        body = json.loads(event['body'])
        name = body['name']
        email = body['email']
        message = body['message']

        # Send email via SES
        ses.send_email(
            Source=os.environ['SENDER_EMAIL'],
            Destination={
                'ToAddresses': [os.environ['RECIPIENT_EMAIL']]
            },
            Message={
                'Subject': {'Data': f'Contact Form: {name}'},
                'Body': {
                    'Text': {'Data': f'From: {name} ({email})\n\n{message}'}
                }
            }
        )

        return {
            'statusCode': 200,
            'headers': {
                'Access-Control-Allow-Origin': '*',
                'Content-Type': 'application/json'
            },
            'body': json.dumps({'message': 'Email sent successfully'})
        }
    except Exception as e:
        return {
            'statusCode': 500,
            'headers': {'Access-Control-Allow-Origin': '*'},
            'body': json.dumps({'error': str(e)})
        }

Frontend JavaScript

contact-form.js JAVASCRIPT

const form = document.getElementById('contact-form');
const API_URL = 'https://abc123.execute-api.us-east-1.amazonaws.com/prod/contact';

form.addEventListener('submit', async (e) => {
    e.preventDefault();

    const data = {
        name: document.getElementById('name').value,
        email: document.getElementById('email').value,
        message: document.getElementById('message').value
    };

    try {
        const response = await fetch(API_URL, {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify(data)
        });

        if (response.ok) {
            alert('Message sent successfully!');
            form.reset();
        } else {
            throw new Error('Failed to send message');
        }
    } catch (error) {
        alert('Error: ' + error.message);
    }
});

IAM Policy for Lambda

lambda-ses-policy.json JSON

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "ses:SendEmail",
                "ses:SendRawEmail"
            ],
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Action": [
                "logs:CreateLogGroup",
                "logs:CreateLogStream",
                "logs:PutLogEvents"
            ],
            "Resource": "arn:aws:logs:*:*:*"
        }
    ]
}

What You'll Learn

API Gateway REST API creation and configuration
Lambda function development and deployment
Email sending with Amazon SES
CORS configuration for cross-origin requests
IAM roles and permissions for Lambda