Inbound Email (SMTP) to Webhook

Author: Martin Alexander - LinkedIn

A simple, efficient script that provides an SMTP server to receive emails, parse content (including headers), store attachments in Amazon S3, and forward email content to a webhook. Graceful handling of multiple concurrent SMTP sessions and webhook requests.

Features

SMTP server to receive emails concurrently
Parses incoming emails using mailparser
Uploads attachments to Amazon S3
Forwards parsed email content to a specified webhook
Configurable via environment variables
Handles large attachments gracefully
Robust queue system for processing multiple emails and webhook requests simultaneously

Prerequisites

Node.js (v18 or later recommended)
If saving attachments, an Amazon Web Services (AWS) account with S3 access or a compatible system
A HTTP(s) webhook endpoint to receive the processed emails

Installation

Clone this repository:

git clone https://github.com/sendbetter/inbound-email.git
cd inbound-email

Install dependencies:
```
npm install
```
Copy the .env.example file to .env and set the required configuration: (eg. mv .env.example .env)
- MAX_FILE_SIZE: Maximum size of attachments to process, in bytes (default: 5MB)
- AWS_REGION: Your AWS region
- AWS_ACCESS_KEY_ID: Your AWS access key ID
- AWS_SECRET_ACCESS_KEY: Your AWS secret access key
- S3_BUCKET_NAME: The name of your S3 bucket for storing attachments
- PORT: The port for the SMTP server to listen on (default: 25)
- WEBHOOK_URL: The URL where parsed emails will be sent (required)
- SMTP_SECURE: Set to 'true' for TLS support (default: false)
- WEBHOOK_CONCURRENCY: Number of concurrent webhook requests (default: 5)

Usage

Start the server:

npm start

The SMTP server will start and listen on the specified port (default: 25) on all network interfaces.

You can use pm2 or supervisor to keep the server running after restart. Example: pm2 start server.js

Sample Use Cases

Email to Ticket System: Use this bridge to receive support emails and automatically create tickets in your helpdesk system via the webhook.
Document Processing: Receive emails with document attachments, store them in S3, and trigger a document processing pipeline through the webhook.
Email Marketing Analysis: Collect incoming emails from a campaign, store any images or attachments, and send the content to an analytics system for processing.
Automated Reporting: Set up an email address that receives automated reports, stores them in S3, and notifies your team via the webhook.
DMARC Reporting: Receive DMARC reports via email and store them in S3.

Using inbound parse for something interesting? Please let me know, I'd love to hear about it.

Todo

Rate limiting
Log Storage

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the MIT License. This means you are free to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the software, including for commercial purposes.

Disclaimer

Please ensure you have the necessary permissions and security measures in place when deploying an SMTP server. Depending on your firewall configuration, you may be exposing this service to the internet.

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