Project structure

Repository

node-mail-server/
├── server/          Node mail server (receiving, sending, bounces, JSON API), plus go-mta/, imap/ and demo/
├── outbound/        KumoMTA sending engine
│   ├── policy/      Lua and TOML, mounted at /opt/kumomta/etc/policy
│   ├── .env.example
│   └── README.md
├── relay/           KumoMTA public relay, one login and webhook per account
│   ├── policy/      Lua, mounted at /opt/kumomta/etc/policy
│   ├── .env.example
│   └── README.md
├── deploy/          docker-compose.yml
├── scripts/         setup.js, send-mail.js, run.sh
├── assets/images/   Screenshots used by the README
├── docs/            This documentation site
└── README.md

Node mail server

server/
├── src/             TypeScript source
├── config/          mail.config.json and smtp-messages.json, reloaded while the server runs
├── go-mta/          Go delivery service (standard library only)
├── imap/            Go IMAP server (Gluon)
├── demo/            Small example projects
├── public/          Static files and icons
├── Dockerfile
├── .env.example
├── package.json
└── tsconfig.json

`server/src`

Folder	Contents
`main.ts`, `start.ts`	`main.ts` starts the servers. `start.ts` generates DNS records.
`config/`	`env.ts` (the only file that reads environment variables), `constants.ts` (fixed values and the default settings), `mailConfig.ts` and `smtpMessages.ts` (the JSON files), and `jsonConfig.ts` (loading, validating and reloading them).
`interfaces/`	TypeScript types for DNS records, mail data and PGP keys.
`lib/`	Helpers (email address parsing, raw message handling, the TTL cache, HTTP authentication), logging, SMTP type extensions and `workers/`, the worker thread pool and its tasks.
`server/`	`IncomingServer.ts` (port 25), `OutgoingServer.ts` (port 587), `BounceServer.ts` (bounce SMTP), `BounceWebhookServer.ts` (bounce HTTP) and `ApiServer.ts` (JSON send API). `index.ts` starts them all and shuts them down.
`server/config/`	DNS checking and generation, mail composing (`MailComposer.ts`), authentication (`MailAuth.ts`), spam filtering and PGP in `encryption/`.
`server/mta/`	Mail delivery: `node-mta.ts`, the outbound queue (`OutboundQueue.ts`) and the drivers in `drivers/`.
`server/plugins/`	Filters, image proxy, rate limiter and tracking protection.
`services/`	`IncomingMailHandler.ts`, `IncomingPolicy.ts`, `OutgoingMailHandler.ts`, `OutgoingPipeline.ts`, `JsonMailHandler.ts`, `BounceMailHandler.ts`, `BounceWebhookHandler.ts`, `IcsEvents.ts` and `MeetingService.ts`.
`services/bounce/`	`DsnProcessor.ts`, `BounceProcessor.ts`, `BounceRegistry.ts`, `SuppressionList.ts` and `DsnBuilder.ts`.

Files that hold secrets

These are in .gitignore. Commit only the .example versions.

File	Contains
`server/.env`	Hostnames, TLS paths, DKIM and PGP keys, relay, Go MTA and KumoMTA passwords, and the API and bounce tokens.
`outbound/.env`	KumoMTA settings, DKIM service key, webhook secret.
`outbound/policy/users.lua`	SMTP usernames and passwords. Start from `users.example.lua`.
`relay/.env`	Relay settings and the DKIM service key.
`relay/policy/users.lua`	Relay accounts: passwords, domains and webhook secrets. Start from `users.example.lua`.
`server/records.json`	Generated DNS records, including the DKIM private key.
`server/spool/`	Queued mail, bounce tracking records and the suppression list.
`.key`, `.pem`, `outbound/dkim/`, `relay/dkim/`, `relay/tls/`	Private keys and certificates.

Scripts

Script	What it does
`scripts/run.sh`	Runs `setup.js`.
`scripts/setup.js`	Asks for your domain and IP, writes `server/.env` and generates DNS records.
`scripts/send-mail.js`	Sends one DKIM-signed test message straight to a recipient's MX server.

Repository

Node mail server

server/src

Files that hold secrets

Scripts

On this page

`server/src`