Forward SMS to email via Twilio and Mailgun

Back in 2017 Phil Nash wrote a very nice blog post for Twilio called Forward incoming SMS messages to email with Node.js, SendGrid and Twilio Functions. I used this exact setup this year for Ratio because I wanted a dedicated phone number for the business. Voice calls are forwarded directly to my mobile using TwiML Bins via the following simple bin:

<?xml version="1.0" encoding="UTF-8"?>
<Response>
  <Dial>+1971221xxxx</Dial>
</Response>

Back to SMS forwarding... we don't get many SMS messages and instead of warning us via email, SendGrid just closed the account. So for some months we weren't getting SMS messages forwarded to our Google Group inbox. Even though I added a credit card, they could not reactivate it, so here I am with a port to Mailgun.

So, same basic steps as Phil's blog post except Functions/Functions are now Functions/Services which you can find here.

Create a new function at path /forward.

Under Dependencies add mailgun.js version 4.1.1 and form-data version 4.0.0.

Under Environment Variables add MAILGUN_DOMAIN, MAILGUN_API_KEY, FROM_EMAIL_ADDRESS, and TO_EMAIL_ADDRESS.

I based this function body on the Mailgun example:

exports.handler = function(context, event, callback) {
  const API_KEY = context.MAILGUN_API_KEY;
  const DOMAIN = context.MAILGUN_DOMAIN;

  const formData = require('form-data');
  const Mailgun = require('mailgun.js');

  const mailgun = new Mailgun(formData);
  const client = mailgun.client({username: 'api', key: API_KEY});

  const messageData = {
    from: context.FROM_EMAIL_ADDRESS,
    to: context.TO_EMAIL_ADDRESS,
    subject: `New SMS message from: ${event.From}`,
    text: event.Body
  };

  client.messages.create(DOMAIN, messageData)
  .then((res) => {
      let twiml = new Twilio.twiml.MessagingResponse();
      callback(null, twiml);
  })
  .catch((err) => {
    console.error(err);
    callback(err);
  });
};

Make sure you hooked it up to the correct phone number, then test it out by sending an SMS message to your Twilio number. If you need to debug, look in the Messaging logs in Twilio and the Mailgun Sending/Logs.

If you run into issues or have feedback, please don't hesitate to send me an email if you know it, or mention me on Twitter. Thanks!