AWS Lambda Quickstart

Prerequisites

To get the most out of this guide, you’ll need to:

Create a SendPost Account
AWS Account with Lambda access
A Sub-Account API Key from your SendPost dashboard

You can find your API keys in your SendPost Dashboard. Make sure to use your Sub-Account API Key for sending emails.

1. Node.js Lambda Function

Install Dependencies

Create a package.json file:

JSON

{
  "name": "sendpost-lambda",
  "version": "1.0.0",
  "dependencies": {
    "sendpost-js-sdk": "^1.0.0"
  }
}

Install dependencies:

npm

npm install

Basic Lambda Function

Create index.js:

JavaScript

const sendpost = require('sendpost-js-sdk');

const emailApi = new sendpost.EmailApi();
const API_KEY = process.env.SENDPOST_API_KEY;

exports.handler = async (event) => {
  try {
    const { to, subject, htmlBody, textBody } = JSON.parse(event.body || event);
    
    const emailMessage = new sendpost.EmailMessage();
    emailMessage.from = {
      email: 'hello@playwithsendpost.io',
      name: 'SendPost'
    };
    emailMessage.to = [{ email: to }];
    emailMessage.subject = subject;
    emailMessage.htmlBody = htmlBody;
    emailMessage.textBody = textBody || htmlBody.replace(/<[^>]*>/g, '');
    emailMessage.trackOpens = true;
    emailMessage.trackClicks = true;

    const response = await emailApi.sendEmail(API_KEY, { emailMessage });

    return {
      statusCode: 200,
      body: JSON.stringify({
        success: true,
        messageId: response.messageId
      })
    };
  } catch (error) {
    console.error('SendPost error:', error);
    return {
      statusCode: 500,
      body: JSON.stringify({
        success: false,
        error: error.message
      })
    };
  }
};

Environment Variables

In AWS Lambda Console, add environment variables:

SENDPOST_API_KEY: your_sub_account_api_key

Deploy with AWS CLI

zip -r function.zip index.js node_modules package.json
aws lambda update-function-code \
  --function-name sendpost-email \
  --zip-file fileb://function.zip

2. Python Lambda Function

Install Dependencies

Create requirements.txt:

sendpost-python-sdk

Basic Lambda Function

Create lambda_function.py:

Python

import json
import os
import sendpost_python_sdk
from sendpost_python_sdk.api import EmailApi
from sendpost_python_sdk.models import EmailMessageObject, EmailAddress, Recipient

def lambda_handler(event, context):
    try:
        # Parse request body
        if isinstance(event.get('body'), str):
            body = json.loads(event['body'])
        else:
            body = event
        
        to = body.get('to')
        subject = body.get('subject')
        html_body = body.get('htmlBody')
        text_body = body.get('textBody')
        
        # Configure SendPost
        configuration = sendpost_python_sdk.Configuration(
            host="https://api.sendpost.io/api/v1"
        )
        configuration.api_key['subAccountAuth'] = os.environ['SENDPOST_API_KEY']
        
        with sendpost_python_sdk.ApiClient(configuration) as api_client:
            email_message = EmailMessageObject()
            email_message.var_from = EmailAddress(
                email='hello@playwithsendpost.io',
                name='SendPost'
            )
            email_message.to = [Recipient(email=to)]
            email_message.subject = subject
            email_message.html_body = html_body
            email_message.text_body = text_body or html_body.replace(r'<[^>]+>', '')
            email_message.track_opens = True
            email_message.track_clicks = True
            
            response = EmailApi(api_client).send_email(email_message)[0]
            
            return {
                'statusCode': 200,
                'body': json.dumps({
                    'success': True,
                    'messageId': response.message_id
                })
            }
    except Exception as e:
        print(f'SendPost error: {str(e)}')
        return {
            'statusCode': 500,
            'body': json.dumps({
                'success': False,
                'error': str(e)
            })
        }

Deploy with AWS CLI

pip install -r requirements.txt -t .
zip -r function.zip lambda_function.py sendpost_python_sdk
aws lambda update-function-code \
  --function-name sendpost-email-python \
  --zip-file fileb://function.zip

3. Common Use Cases

Welcome Email Lambda

Node.js version:

JavaScript

exports.handler = async (event) => {
  try {
    const { email, firstName } = JSON.parse(event.body);
    
    const emailMessage = new sendpost.EmailMessage();
    emailMessage.from = {
      email: 'hello@playwithsendpost.io',
      name: 'SendPost'
    };
    emailMessage.to = [{
      email,
      name: firstName,
      customFields: { firstName }
    }];
    emailMessage.subject = 'Welcome {{firstName}}!';
    emailMessage.htmlBody = `
      <h1>Welcome, {{firstName}}!</h1>
      <p>Thank you for joining us. We're excited to have you on board.</p>
      <p><a href="{{unsubscribe}}">Unsubscribe</a></p>
    `;
    emailMessage.groups = ['welcome'];

    const response = await emailApi.sendEmail(API_KEY, { emailMessage });

    return {
      statusCode: 200,
      body: JSON.stringify({
        success: true,
        messageId: response.messageId
      })
    };
  } catch (error) {
    return {
      statusCode: 500,
      body: JSON.stringify({ success: false, error: error.message })
    };
  }
};

Password Reset Email Lambda

Python version:

Python

def lambda_handler(event, context):
    try:
        body = json.loads(event['body']) if isinstance(event.get('body'), str) else event
        email = body['email']
        reset_token = body['resetToken']
        first_name = body.get('firstName', 'User')
        app_url = os.environ.get('APP_URL', 'https://yourapp.com')
        reset_url = f"{app_url}/reset-password?token={reset_token}"
        
        configuration = sendpost_python_sdk.Configuration(
            host="https://api.sendpost.io/api/v1"
        )
        configuration.api_key['subAccountAuth'] = os.environ['SENDPOST_API_KEY']
        
        with sendpost_python_sdk.ApiClient(configuration) as api_client:
            email_message = EmailMessageObject()
            email_message.var_from = EmailAddress(
                email='hello@playwithsendpost.io',
                name='SendPost'
            )
            email_message.to = [Recipient(
                email=email,
                name=first_name,
                custom_fields={
                    'firstName': first_name,
                    'resetUrl': reset_url
                }
            )]
            email_message.subject = 'Reset Your Password'
            email_message.html_body = f'''
                <h2>Hello {{firstName}},</h2>
                <p>Click the link below to reset your password:</p>
                <p><a href="{{resetUrl}}">Reset Password</a></p>
                <p>This link expires in 1 hour.</p>
            '''
            email_message.groups = ['password-reset']
            
            response = EmailApi(api_client).send_email(email_message)[0]
            
            return {
                'statusCode': 200,
                'body': json.dumps({
                    'success': True,
                    'messageId': response.message_id
                })
            }
    except Exception as e:
        return {
            'statusCode': 500,
            'body': json.dumps({'success': False, 'error': str(e)})
        }

4. API Gateway Integration

Create API Gateway Endpoint

Create a new API Gateway REST API
Create a POST method
Set integration type to Lambda Function
Select your Lambda function
Deploy to a stage

Example Request

curl -X POST https://your-api-id.execute-api.region.amazonaws.com/stage/send-email \
  -H "Content-Type: application/json" \
  -d '{
    "to": "user@example.com",
    "subject": "Hello from Lambda",
    "htmlBody": "<h1>Hello!</h1><p>This email was sent from AWS Lambda.</p>"
  }'

5. Using Lambda Layers (Node.js)

Create Layer

mkdir -p nodejs/node_modules
npm install sendpost-js-sdk --prefix nodejs/
zip -r sendpost-layer.zip nodejs/
aws lambda publish-layer-version \
  --layer-name sendpost-sdk \
  --zip-file fileb://sendpost-layer.zip \
  --compatible-runtimes nodejs18.x nodejs20.x

Use Layer in Lambda

Attach the layer to your Lambda function in the AWS Console or via CLI:

aws lambda update-function-configuration \
  --function-name sendpost-email \
  --layers arn:aws:lambda:region:account:layer:sendpost-sdk:1

6. Error Handling & Logging

Enhanced Error Handling

JavaScript

exports.handler = async (event) => {
  const requestId = event.requestContext?.requestId || 'unknown';
  
  try {
    // Validate input
    if (!event.body) {
      throw new Error('Request body is required');
    }
    
    const body = JSON.parse(event.body);
    if (!body.to || !body.subject || !body.htmlBody) {
      throw new Error('Missing required fields: to, subject, htmlBody');
    }
    
    // Send email
    const response = await emailApi.sendEmail(API_KEY, { emailMessage });
    
    console.log(`Email sent successfully: ${response.messageId}`, {
      requestId,
      to: body.to
    });
    
    return {
      statusCode: 200,
      headers: {
        'Content-Type': 'application/json',
        'X-Request-Id': requestId
      },
      body: JSON.stringify({
        success: true,
        messageId: response.messageId,
        requestId
      })
    };
  } catch (error) {
    console.error('Lambda error:', {
      requestId,
      error: error.message,
      stack: error.stack
    });
    
    return {
      statusCode: error.message.includes('required') ? 400 : 500,
      headers: {
        'Content-Type': 'application/json',
        'X-Request-Id': requestId
      },
      body: JSON.stringify({
        success: false,
        error: error.message,
        requestId
      })
    };
  }
};

7. Testing Locally

Using SAM CLI

Create template.yaml:

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31

Resources:
  SendPostEmailFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: index.handler
      Runtime: nodejs20.x
      Environment:
        Variables:
          SENDPOST_API_KEY: your_api_key
      Events:
        SendEmail:
          Type: Api
          Properties:
            Path: /send-email
            Method: post

Test locally:

sam local start-api

Using Lambda Runtime Interface Emulator

docker run -p 9000:8080 \
  -e SENDPOST_API_KEY=your_api_key \
  -v "$PWD":/var/task \
  public.ecr.aws/lambda/nodejs:20

Test:

curl -X POST "http://localhost:9000/2015-03-31/functions/function/invocations" \
  -d '{"body": "{\"to\":\"user@example.com\",\"subject\":\"Test\",\"htmlBody\":\"<h1>Test</h1>\"}"}'

Make sure your sender email domain is verified in your SendPost account before sending emails.

8. Next Steps

Explore more examples and use cases:

AWS Lambda Documentation

Learn more about AWS Lambda

SendPost JavaScript SDK

View the official SDK package on npm

SendPost Python SDK

View the official SDK package on PyPI

Quickstart Example

Complete working example from this quickstart guide

Documentation

Guides

Quickstarts

Common Use Cases

Prerequisites

1. Node.js Lambda Function

Install Dependencies

Basic Lambda Function

Environment Variables

Deploy with AWS CLI

2. Python Lambda Function

Install Dependencies

Basic Lambda Function

Deploy with AWS CLI

3. Common Use Cases

Welcome Email Lambda

Password Reset Email Lambda

4. API Gateway Integration

Create API Gateway Endpoint

Example Request

5. Using Lambda Layers (Node.js)

Create Layer

Use Layer in Lambda

6. Error Handling & Logging

Enhanced Error Handling

7. Testing Locally

Using SAM CLI

Using Lambda Runtime Interface Emulator

8. Next Steps

AWS Lambda Documentation

SendPost JavaScript SDK

SendPost Python SDK

Quickstart Example

​Prerequisites

​1. Node.js Lambda Function

​Install Dependencies

​Basic Lambda Function

​Environment Variables

​Deploy with AWS CLI

​2. Python Lambda Function

​Install Dependencies

​Basic Lambda Function

​Deploy with AWS CLI

​3. Common Use Cases

​Welcome Email Lambda

​Password Reset Email Lambda

​4. API Gateway Integration

​Create API Gateway Endpoint

​Example Request

​5. Using Lambda Layers (Node.js)

​Create Layer

​Use Layer in Lambda

​6. Error Handling & Logging

​Enhanced Error Handling

​7. Testing Locally

​Using SAM CLI

​Using Lambda Runtime Interface Emulator

​8. Next Steps

AWS Lambda Documentation

SendPost JavaScript SDK

SendPost Python SDK

Quickstart Example

Prerequisites

1. Node.js Lambda Function

Install Dependencies

Basic Lambda Function

Environment Variables

Deploy with AWS CLI

2. Python Lambda Function

Install Dependencies

Basic Lambda Function

Deploy with AWS CLI

3. Common Use Cases

Welcome Email Lambda

Password Reset Email Lambda

4. API Gateway Integration

Create API Gateway Endpoint

Example Request

5. Using Lambda Layers (Node.js)

Create Layer

Use Layer in Lambda

6. Error Handling & Logging

Enhanced Error Handling

7. Testing Locally

Using SAM CLI

Using Lambda Runtime Interface Emulator

8. Next Steps