send-email.js

// Email callback handler
    const emailCallback = (emailResult) => {
        let result = null
        if (emailResult.error) {
            result = {
                "text": "There is problem!",
                "attachments": [
                    {
                        "text": JSON.stringify(emailResult.error)
                    }
                ]
            }
        } else {
            result = {
                "text": "Email has been sent: " + emailInfo.emails + ' : ' + emailInfo.subject,
                "attachments": [
                    {
                        "text": htmlBody
                    }
                ]
            }
        }
        callback(undefined, result)
    }

    // Send email 
    utils.sendEmail(emailInfo.emails, emailInfo.subject, htmlBody, emailCallback)