Node.js

export SECURESSMTP_API_KEY="qcs_live_..."

// securessmtp.js (Node.js 18 or later)
const API_URL = 'https://securessmtp.com/api/v1/mail/send';

export class SecureSMTPError extends Error {
  constructor(reason, status, result) {
    super(`SecureSMTP: ${reason} (HTTP ${status})`);
    this.name = 'SecureSMTPError';
    this.reason = reason;
    this.status = status;
    this.result = result;
  }
}

export async function sendEmail(message) {
  const apiKey = process.env.SECURESSMTP_API_KEY;
  if (!apiKey) throw new Error('SECURESSMTP_API_KEY is not set');

  const res = await fetch(API_URL, {
    method: 'POST',
    headers: {
      'x-securessmtp-api-key': apiKey,
      'Content-Type': 'application/json',
    },
    body: JSON.stringify(message),
    signal: AbortSignal.timeout(30_000),
  });

  // The API always answers JSON with an "ok" field. A body that is not JSON
  // (for example a 413 from the web server) is treated as a failure too.
  const result = await res.json().catch(() => ({ ok: false }));
  if (!result.ok) {
    throw new SecureSMTPError(result.reason ?? result.error ?? 'request_failed', res.status, result);
  }
  return result; // { ok: true, sent: true, mode: 'relay' | 'domain', message_id: '<...>' }
}

import { sendEmail } from './securessmtp.js';

const result = await sendEmail({
  to: '[email protected]',
  subject: 'Your order has shipped',
  html: '<p>Your order is on its way.</p>',
  text: 'Your order is on its way.',
  from: { name: 'Acme Store' },
  reply_to: '[email protected]',
});

console.log(result.message_id);

import { readFile } from 'node:fs/promises';
import { sendEmail } from './securessmtp.js';

const pdf = await readFile('./invoice-1042.pdf');

await sendEmail({
  to: '[email protected]',
  subject: 'Invoice 1042',
  text: 'Your invoice is attached.',
  from: { name: 'Acme Store' },
  attachments: [
    {
      filename: 'invoice-1042.pdf',
      content: pdf.toString('base64'),
      content_type: 'application/pdf',
    },
  ],
});

import { sendEmail, SecureSMTPError } from './securessmtp.js';

try {
  await sendEmail({ to: '[email protected]', subject: 'Hello', text: 'Hi there.' });
} catch (err) {
  if (err instanceof SecureSMTPError) {
    switch (err.reason) {
      case 'rate_limited':
        // More than 120 sends from this site in 60 seconds. Wait a minute, then retry.
        break;
      case 'over_quota':
        // The account's monthly email count is used up.
        break;
      case 'send_failed':
        console.error('Not sent:', err.result.error);
        break;
      default:
        // 400/401/403: fix the request or the key. Retrying will not help.
        console.error(err.message, err.result.details ?? '');
    }
  } else {
    // Network error or timeout. The email may or may not have been sent.
    console.error(err);
  }
}

import nodemailer from 'nodemailer';

const transporter = nodemailer.createTransport({
  host: 'smtp.securessmtp.com',
  port: 587,
  secure: false, // STARTTLS on 587. For port 465 use: port: 465, secure: true
  requireTLS: true,
  auth: {
    user: 'securessmtp',
    pass: process.env.SECURESSMTP_API_KEY,
  },
});

const info = await transporter.sendMail({
  from: '"Acme Store" <[email protected]>',
  to: '[email protected]',
  subject: 'Your order has shipped',
  text: 'Your order is on its way.',
  html: '<p>Your order is on its way.</p>',
  attachments: [{ filename: 'invoice-1042.pdf', path: './invoice-1042.pdf' }],
});

console.log(info.response);

try {
  await transporter.sendMail(message);
} catch (err) {
  // err.responseCode is the SMTP reply code, err.response the full reply text.
  if (err.responseCode >= 400 && err.responseCode < 500) {
    // Temporary (e.g. 450 rate limit). Retry in a minute.
  } else if (err.responseCode === 535) {
    // Wrong API key in the password.
  }
  console.error(err.responseCode, err.response ?? err.message);
}