Yep exactly, since in general the best practice is to create one user per service, it's often named as the product ha ha
Same config here 🙂
It needs a mail server/address to send those mails from. By default NodeBB tries to use the SendMail application for this. As you don't have that installed (I assume) it gives that error. Personally I'm using MailGun (with this plugin) instead of SendMail for this, because SendMail is complicated to set up.