Rust Mailer API

A fast, reliable REST API for sending emails built with Rust and Axum. Send emails via JSON API with support for both plain text and HTML content.

Features

• REST API: Simple JSON endpoints for sending emails
• Multi-format Support: Plain text and HTML emails
• Bulk Email Sending: Send emails to multiple recipients simultaneously
• Configurable: Environment-based configuration
• Fast: Built with Rust and Axum for high performance
• Validation: Email format and content validation
• CORS Enabled: Ready for web applications
• Health Check: Built-in health monitoring endpoint

Setup

1. Clone and Build

git clone <your-repo>
cd rust-mailer
cargo build --release

2. Environment Variables

Create a .env file in the project root:

# Email Configuration (Required)
EMAIL_ADDRESS=your-email@gmail.com
APP_PASSWORD=your-app-password-here

# SMTP Configuration (Optional)
SMTP_SERVER=smtp.gmail.com
SMTP_PORT=587

# Server Configuration (Optional)
PORT=6969

3. Gmail Setup

For Gmail, you'll need an App Password:

1. Enable 2-Factor Authentication on your Google account
2. Go to Google Account Settings → Security → App passwords
3. Generate a new app password for "Mail"
4. Use this password in the APP_PASSWORD environment variable

Running the Server

cargo run

The server will start on http://0.0.0.0:6969 (or your configured PORT).

API Documentation

Health Check

GET /

curl http://localhost:6969/

Response:

{
  "status": "healthy",
  "service": "rust-mailer-api",
  "version": "0.1.0"
}

Send Single Email

POST /send-email

Request Body:

{
  "to": "recipient@example.com",
  "subject": "Hello from Rust Mailer!",
  "body": "This is a plain text message.",
  "html": "<h1>Hello!</h1><p>This is an <strong>HTML</strong> message.</p>"
}

Fields:

• to (required): Recipient email address
• subject (required): Email subject
• body (required): Plain text content
• html (optional): HTML content for rich emails

Success Response (200):

{
  "success": true,
  "message": "Email sent successfully",
  "email_sent_to": "recipient@example.com"
}

Error Response (400/500):

{
  "success": false,
  "message": "Invalid email address format",
  "email_sent_to": null
}

Send Bulk Emails

POST /send-bulk-email

Request Body:

{
  "recipients": [
    "user1@example.com",
    "user2@example.com",
    "user3@example.com"
  ],
  "subject": "Bulk Email Test",
  "body": "This is a bulk email message sent to multiple recipients.",
  "html": "<h1>Bulk Email</h1><p>This is a <strong>bulk email</strong> message.</p>"
}

Fields:

• recipients (required): Array of recipient email addresses
• subject (required): Email subject
• body (required): Plain text content
• html (optional): HTML content for rich emails

Success Response (200/206):

{
  "total_emails": 3,
  "successful": 2,
  "failed": 1,
  "results": [
    {
      "email": "user1@example.com",
      "success": true,
      "message": "Email sent successfully"
    },
    {
      "email": "user2@example.com",
      "success": false,
      "message": "SMTP connection error"
    }
  ]
}

Testing Examples

Plain Text Single Email

curl -X POST http://localhost:6969/send-email \
  -H "Content-Type: application/json" \
  -d '{
    "to": "test@example.com",
    "subject": "Test Email",
    "body": "This is a test message from Rust Mailer API!"
  }'

Bulk Email

curl -X POST http://localhost:6969/send-bulk-email \
  -H "Content-Type: application/json" \
  -d '{
    "recipients": [
      "user1@example.com",
      "user2@example.com",
      "user3@example.com"
    ],
    "subject": "Bulk Email Test",
    "body": "This is a bulk email message sent to multiple recipients."
  }'

HTML Email

curl -X POST http://localhost:6969/send-email \
  -H "Content-Type: application/json" \
  -d '{
    "to": "test@example.com",
    "subject": "Beautiful HTML Email",
    "body": "This is the plain text version.",
    "html": "<div style=\"font-family: Arial, sans-serif;\"><h1 style=\"color: #333;\">Welcome!</h1><p>This is a <strong>beautiful</strong> HTML email with <em>styling</em>.</p><button style=\"background: #007bff; color: white; padding: 10px 20px; border: none; border-radius: 5px;\">Click Me!</button></div>"
  }'

Using JavaScript/Node.js

const response = await fetch('http://localhost:6969/send-email', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    to: 'user@example.com',
    subject: 'Welcome to our service!',
    body: 'Thanks for signing up!',
    html: '<h2>Welcome!</h2><p>Thanks for <strong>signing up</strong>!</p>'
  })
});

const result = await response.json();
console.log(result);

Using Python

import requests

response = requests.post('http://localhost:6969/send-email', json={
    'to': 'user@example.com',
    'subject': 'Python Test Email',
    'body': 'This email was sent from Python!',
    'html': '<h1>Python Email</h1><p>This email was sent from <strong>Python</strong>!</p>'
})

print(response.json())

Configuration Options

Environment Variable	Default	Description
EMAIL_ADDRESS	Required	Your email address (sender)
APP_PASSWORD	Required	App password for authentication
SMTP_SERVER	smtp.gmail.com	SMTP server hostname
SMTP_PORT	587	SMTP server port
PORT	6969	API server port

Error Handling

The API provides detailed error messages for various scenarios:

• 400 Bad Request: Invalid email format, empty subject/body
• 500 Internal Server Error: SMTP connection issues, authentication failures

Status Codes

• 200 - Email sent successfully
• 206 - Partial success in bulk email sending
• 400 - Bad request (validation errors)
• 500 - Internal server error (SMTP issues)

Future Enhancements

• Bulk email sending
• Email scheduling
• Delivery tracking
• Rate limiting
• Authentication/API keys
• Multiple email providers
• Email history/logging

---

Happy Emailing!