Delivery Confirmation Example

Consider a scenario, where you have an automated process that sends emails. You may wish to test that this automated process is sending emails and they are being received. Mailsac provides an API so you can check that these emails are being received.

These examples sends emails to using an SMTP server.

Validate receipt using Node.js Javascript. Full Node.js Example.
const assert = require("assert");
const nodemailer = require("nodemailer");
const request = require("supertest");

const mailsacAPIKey = process.env.MAILSAC_API_KEY || ''; // Generated by mailsac. See
const mailsacToAddress = process.env.MAILSAC_TO_ADDRESS || ''; // Mailsac email address where the email will be sent
const smtpUserName = process.env.SMTP_USER || ''; // Username for smtp server authentication
const smtpPassword = process.env.SMTP_PASSWORD || ''; // Password for smtp server authentication
const smtpHost = process.env.SMTP_HOST || ''; // hostname of the smtp server
const smtpPort = process.env.SMTP_PORT || 587; // port the smtp is listening on

// Assumes SMTP relay requires authentication
if (mailsacAPIKey == '' || mailsacToAddress == '' || smtpUserName == ''  || smtpPassword == '' || smtpHost == '' ) {
  throw new Error('Missing required variable')
const wait = (millis) => new Promise((resolve) => setTimeout(resolve, millis));

describe("send email to mailsac", function () {
  this.timeout(50000); // test can take a long time to run. This increases the default timeout for mocha

  /* delete all messages in the inbox after the test runs to prevent leaky tests.
       This requires the inbox to private, which is a paid feature of Mailsac.
       The afterEach section could be omitted if using a public address
  afterEach(() =>
      .set("Mailsac-Key", mailsacAPIKey)

  it("sends email with link to website", async () => {
    // create a transporter object using the default SMTP transport
    const transport = nodemailer.createTransport({
      host: smtpHost,
      port: smtpPort,
      auth: {
        user: smtpUserName,
        pass: smtpPassword,
    // send mail using the defined transport object
    const result = await transport.sendMail({
      from: smtpUserName, // sender address
      to: mailsacToAddress, // recipient address
      subject: "Hello!",
      text: "Check out",
      html: "Check out <a href>My website</a>",

    // logs the messageId of the email, confirming the email was submitted to the smtp server
    console.log("Sent email with messageId: ", result.messageId);

    // Check email in the inbox 10x, waiting 5 secs in between. Once we find mail, abort the loop.
    let messages = [];
    for (let i = 0; i < 10; i++) {
      // returns the JSON array of email message objects from mailsac.
      const res = await request("")
        .set("Mailsac-Key", mailsacAPIKey);

      messages = res.body;
      if (messages.length > 0) {
      await wait(4500);
    assert(messages.length, "Never received messages!");

    // After a message is retrieved from mailsac, the JSON object is checked to see if the link was parsed from the email and it is the correct link
    const link = messages[0].links.find((l) => "");
    assert(link, "Missing / Incorrect link in email");