Prerequisites

Before you begin, ensure you have:

• Node.js (v22.14.0 or newer) installed on your system ([pnpm][1])

• pnpm (v10.7.0 as declared) globally available. If not, install via:

  npm install -g pnpm

  or using the standalone install script from the pnpm docs ([pnpm][1]).

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Installation

1. Clone the repo

   git clone <your-repo-url> mail-service
   cd mail-service

2. Install dependencies

   pnpm install

   This will read your package.json and pnpm-lock.yaml, creating a fast, content-addressable package store ([pnpm][2]).

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Available Scripts

All commands assume you’re in the project root:

Script	What it does	How to run
start:smtp	Launches the SMTP server on port 1025	pnpm run start:smtp
start:imap	Launches the IMAP server on port 143	pnpm run start:imap
test:sender	Sends a test email via local SMTP	pnpm run test:sender

You can also shorten pnpm run start:smtp to pnpm start:smtp—pnpm aliases script names as top-level commands when there’s no naming conflict ([pnpm][3]).

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IMAP Server & Privileged Port 143

On Linux, binding to ports below 1024 (e.g. IMAP’s default port 143) is restricted to the root user or processes with the CAP_NET_BIND_SERVICE capability ([Stack Overflow][4], [Server Fault][5]). Otherwise, you’ll see:

Error: listen EACCES: permission denied 0.0.0.0:143

Options to Satisfy Port Binding

1. Run as root

   sudo pnpm run start:imap

2. Grant CAP_NET_BIND_SERVICE to Node.js binary (allows non-root binding):

   sudo setcap 'cap_net_bind_service=+ep' "$(which node)"
   pnpm run start:imap

   This is minimally invasive—only grants the bind privilege ([Unix & Linux Stack Exchange][6]).

3. Use a non-privileged port (≥ 1025) for pure local testing by editing src/imap-server.js:

   net.createServer(handler).listen(8143, …);

   and adjust your client accordingly.

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Project Structure

mail-service/
├─ node_modules/
├─ src/
│  ├─ email-store.js       # Shared in-memory email array
│  ├─ smtp-server.js       # SMTP server (port 1025)
│  ├─ imap-server.js       # IMAP server (port 143)
│  └─ sender.js            # Nodemailer test client
├─ package.json            # Scripts & dependencies
└─ pnpm-lock.yaml          # Exact dependency tree

---

package.json Snippet

{
  "name": "mail-service",
  "version": "1.0.0",
  "main": "src/smtp-server.js",
  "scripts": {
    "start:smtp": "node src/smtp-server.js",
    "start:imap": "node src/imap-server.js",
    "test:sender": "node src/sender.js"
  },
  "packageManager": "[email protected]",
  "dependencies": {
    "smtp-server": "^3.13.6",
    "imap-server": "^0.0.1",
    "mailparser": "^3.7.2",
    "nodemailer": "^7.0.0"
  }
}