send.mjs

// Example: sending example 05's digest email via SMTP using nodemailer.
//
// Run `npm run examples` first (or at least
// `node examples/05-plain-text/run.mjs`) so dist/05-plain-text/digest.html
// and digest.txt exist.
//
// Install nodemailer: npm install nodemailer
// Then configure SMTP settings below.
//
// Alternatives:
//   - SendGrid: @sendgrid/mail
//   - Postmark: postmark
//   - Mailgun: mailgun-js
//   - Amazon SES: @aws-sdk/client-ses

import fs from "node:fs";
import path from "node:path";
import crypto from "node:crypto";
import { fileURLToPath } from "node:url";

// import nodemailer from "nodemailer";

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const htmlPath = path.join(__dirname, "dist/05-plain-text/digest.html");
const textPath = path.join(__dirname, "dist/05-plain-text/digest.txt");

if (!fs.existsSync(htmlPath) || !fs.existsSync(textPath)) {
  console.error("Missing dist/05-plain-text/digest.{html,txt} — run `npm run examples` first.");
  process.exit(1);
}

const html = fs.readFileSync(htmlPath, "utf-8");
const text = fs.readFileSync(textPath, "utf-8");

// const transport = nodemailer.createTransport({
//   host: "smtp.example.com",
//   port: 587,
//   secure: false,
//   auth: { user: "your-username", pass: "your-password" },
// });
//
// const info = await transport.sendMail({
//   from: '"Northwind Coffee" <digest@northwindcoffee.example>',
//   to: "subscriber@example.com",
//   subject: "This week at Northwind Coffee",
//   text,
//   html,
// });
// console.log("sent:", info.messageId);

// What nodemailer builds under the hood, spelled out by hand: a
// multipart/alternative message with the plain-text part first (least
// capable first) and the HTML part second, joined by a MIME boundary.
const boundary = `nwc-${crypto.randomBytes(16).toString("hex")}`;
const message =
  "From: Northwind Coffee <digest@northwindcoffee.example>\r\n" +
  "To: subscriber@example.com\r\n" +
  "Subject: This week at Northwind Coffee\r\n" +
  "MIME-Version: 1.0\r\n" +
  `Content-Type: multipart/alternative; boundary="${boundary}"\r\n` +
  "\r\n" +
  `--${boundary}\r\n` +
  "Content-Type: text/plain; charset=utf-8\r\n" +
  "\r\n" +
  text +
  "\r\n" +
  `--${boundary}\r\n` +
  "Content-Type: text/html; charset=utf-8\r\n" +
  "\r\n" +
  html +
  "\r\n" +
  `--${boundary}--\r\n`;

console.log("SMTP config not set — edit send.mjs with your credentials.");
console.log(`HTML part:      ${Buffer.byteLength(html)} bytes`);
console.log(`Text part:       ${Buffer.byteLength(text)} bytes`);
console.log(`Multipart total: ${Buffer.byteLength(message)} bytes`);