I have my domain in namecheap with an email account too.
I’ve tried to install Discourse in a Vultr and later in a DO server. I was not able to get it sending emails, starting with the admin’s first email, nor with privateemail from my email account at Namecheap for the SMTP settings nor with Sendgrid or Mailgun. I don’t understand what’s the problem, I have tried everything and the credentials are right as I have added Namecheap email to my Google account and can send and receive emails thru it without any problems…