This article on SendGrid is helpful. You do need to set up a separate MX record on a subdomain (or other domain) for inbound "parse" replies.
Unsolved Starting NodeBB Automatically
Best way to go about making NodeBB start automatically on CentOS? I've toyed around with systemd.
Have you looked at PM2? Digitalocean has published quite nice tutorial.
@metalkramp That's perfect!
Do I want to use app.js or loader.js?