I'm not receiving email Node js

I'm try to get an email every time I create a contact .When Create a contact I have to include the email address ,then I should receive an email ,but I don't .It was working before for me but now I don't receive any email every time I create a contact This is the code I wrote :

Index.js

'use strict';

var _ = require('lodash'); var Contact = require('./contact.model');

// Get list of contacts exports.index = function(req, res) {
          // Connect to the db    Contact.find(function (err, contacts) {
    if(err) { return handleError(res, err); }
    return res.json(200, contacts);   });

} ;

// Creates a new contact in datastore. exports.create = function(req, res) {   Contact.create(req.body, function(err, contact) {
    if(err) { return handleError(res, err); }
    return res.json(201, contact);
    contactEvent.publish('create_contact_event', contact);   }); };


function handleError(res, err) {   return res.send(500, err); };

Mail_app.js

var api_key = 'key-83224fdd930ba495d8ee3776e92e8e62';
var domain = 'mg.mydomain95.com';
var mailgun = require('mailgun-js')({apiKey: api_key, domain: domain});
var contactEvent = require('./events');

var  messageHandler = function(m) {
         // The Payload
        var data = {
            from: 'WIT BSc IT <me@wit.ie>',
            to: JSON.parse(m).email,
            subject: 'Welcome',
            text: 'Welcome to the company!!!'
          };

          mailgun.messages().send(data, function (error, body) {
            console.log(body);
          });
        }

contactEvent.subscribe('create_contact_event', messageHandler)

Events.js

'use strict';
// Pubnub service configuration
// ===========================

var PubNub = require('pubnub');

var pubnub = new PubNub({
            publishKey : 'pub-c-90209b1f-dd41-42a1-b64c-ab143ae25a56',
            subscribeKey : 'sub-c-6eed774c-0281-11e7-8437-0619f8945a4f',
            secretKey: "sec-c-NWY5ZjAzYWMtMWIxZi00ZTM2LTg3NGEtMDRjMGExZjI5YzNl",
            ssl: true
});



module.exports = {
  publish: function(channel, message){
    pubnub.publish({
             channel: channel,
             message: JSON.stringify(message)},
             function(status, response) {
               if (status.error) {
                 console.log(status)
               } else {
                 console.log("message Published w/ timetoken", response.timetoken)
               }
             });
  },
  subscribe: function(channel, callback){

    pubnub.addListener({

        message: function(m) {
            // handle message

            var msg = m.message; // The Payload

            callback(msg);
            }
  });
    // Subscribe to the demo_tutorial channel
    pubnub.subscribe({
        channels: [channel]
    });
  }
}

via Russkiy