submail

Submail Architecture

Submail uses a hybrid architecture to provide both a modern web dashboard and a highly performant, custom-built SMTP server.

🏗️ System Overview

The system consists of two main logical components:

1. Web Dashboard (apps/web): A Next.js 14 application providing the user interface.
2. SMTP Bot (apps/bot): A Node.js application that handles incoming emails and Discord notifications.

🔄 Data Flow

1. User Action: User logs in with Discord, creates an alias (e.g., user@example.com).
2. Data Storage: Alias and session data is stored in the database (SQLite/PostgreSQL) via Prisma ORM.
3. Email Receipt: Sender emails user@example.com → Reaches port 25 on the SMTP server.
4. Processing: apps/bot receives the SMTP connection, validates the recipient alias against the DB.
5. Forwarding: If valid, the email is parsed, and a summary is sent to the user’s DM on Discord.

🛡️ Security Features

• Discord Gate: Authentication is strictly handled via Discord OAuth2. Only members of a specific Guild can be allowed access.
• Content Security Policy (CSP): Strict headers to prevent XSS.
• HSTS: Enforces HTTPS connections.
• PII Masking: Functionality to mask personal information in logs.
• Rate Limiting: Uses Upstash Redis to prevent abuse of API endpoints and email flooding.

🗄️ Database Schema

The database is managed by Prisma and shared between both apps. Key models include:

• User: Stores Discord ID and profile info.
• Alias: Stores created email aliases and their status (Active/Paused).
• Log: Audit trail of processed emails.

🐳 Docker Architecture

In a Dockerized environment, both services run as separate containers but share the same network and database volume (if using SQLite).

• web container: Exposes port 3000.
• bot container: Exposes port 25.

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