> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lettr.com/llms.txt
> Use this file to discover all available pages before exploring further.
# AWS Lambda
> Send transactional emails from AWS Lambda functions using Lettr's HTTP API, with no persistent connections or background workers.
Send transactional emails from AWS Lambda using Lettr's HTTP API. Lambda's event-driven architecture pairs perfectly with Lettr — no persistent connections, no background workers, just simple HTTP requests.
Using Cursor? [Jump straight in using this prompt](https://cursor.com/link/prompt?text=Help%20me%20add%20a%20Lettr%20sending%20example%20for%20AWS%20Lambda%2C%20or%20migrate%20my%20current%20Lambda%20email%20sending%20solution%20to%20Lettr%20using%20these%20docs%3A%20https%3A%2F%2Fdocs.lettr.com%2Fquickstart%2Fserverless%2Faws-lambda-quickstart)
## Prerequisites
Before you begin, make sure you have:
Create an API key in the Lettr dashboard
Add and verify your sending domain
You'll also need:
* **AWS account** with Lambda access and appropriate IAM permissions
* **Node.js 18.x or 20.x** runtime
* **AWS CLI** installed and configured (optional, but recommended)
## Quick Setup
Create a new Lambda function in the AWS Console or via AWS CLI:
```bash theme={null}
aws lambda create-function \
--function-name send-email \
--runtime nodejs20.x \
--role arn:aws:iam::YOUR_ACCOUNT_ID:role/lambda-execution-role \
--handler index.handler \
--zip-file fileb://function.zip
```
Set your Lettr API key as an environment variable:
```bash theme={null}
aws lambda update-function-configuration \
--function-name send-email \
--environment "Variables={LETTR_API_KEY=lttr_your_api_key_here,FROM_EMAIL=noreply@yourdomain.com}"
```
For production, use AWS Secrets Manager instead of environment variables. See the [Advanced Guide](/quickstart/serverless/aws-lambda-advanced#using-aws-secrets-manager) for details.
Deploy the function code (see examples below) and test it:
```bash theme={null}
aws lambda invoke \
--function-name send-email \
--payload '{"body":"{\"to\":\"user@example.com\",\"subject\":\"Test\",\"html\":\"Hello!
\"}"}' \
response.json
```
## Node.js Implementation
Install the SDK in your Lambda function:
```bash theme={null}
npm install lettr
```
Then create your handler:
```javascript theme={null}
import { Lettr } from 'lettr';
const lettr = new Lettr(process.env.LETTR_API_KEY);
export const handler = async (event) => {
try {
// Parse request body (API Gateway proxy integration)
const body = JSON.parse(event.body || '{}');
const { to, subject, html, text } = body;
// Validate required fields
if (!to || !subject || (!html && !text)) {
return {
statusCode: 400,
body: JSON.stringify({
error: 'Missing required fields: to, subject, and html or text',
}),
};
}
// Send email via Lettr
const result = await lettr.emails.send({
from: process.env.FROM_EMAIL || 'noreply@yourdomain.com',
to: Array.isArray(to) ? to : [to],
subject,
html,
text,
});
console.log(`Email sent successfully. Request ID: ${result.request_id}`);
return {
statusCode: 200,
headers: {
'Content-Type': 'application/json',
},
body: JSON.stringify({
success: true,
requestId: result.request_id,
accepted: result.accepted,
}),
};
} catch (error) {
console.error('Failed to send email:', error);
return {
statusCode: error.status || 500,
body: JSON.stringify({
error: error.message || 'Internal server error',
}),
};
}
};
```
The Lettr SDK automatically handles retries for transient failures and provides better error messages than raw fetch calls.
## What's Next
Learn about deployment strategies, event triggers, and best practices
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