check-uses-google-mail.js

const domainUsesGoogleMail = domain => {
    return fetch('https://dns.google.com/resolve?name=' + encodeURIComponent(domain) +'&type=MX').then(res => res.json()).then(d => {
        return d.Answer.reduce((acc, val) => {
            return acc || (val.data.indexOf('google.com.') >= 0 || val.data.indexOf('googlemail.com.') >= 0)
        }, false)
    })
}
const showMailServer = domain => {
    domainUsesGoogleMail(domain).then(r => {
        console.log(r ? `${domain} uses Google Mail` : `${domain} does not use Google Mail`)
    })
}
showMailServer('paw.cloud')
showMailServer('l214.com')
showMailServer('rain-blog.com')
showMailServer('microsoft.com')