email-strategy.js

const mailgun = require('mailgun-js')({
    apiKey: api_key,
    domain: domain
});
 
const EmailStrategy = {
    send: function(receiptHtml, userEmail) {
        const emailBody = getEmailBody(receiptHtml, userEmail);
        mailgun.messages().send(emailBody, function (error, body) {
            console.log(body);
        });
    }
}