I have seen some similar posts, however, they are fairly old and don’t quite solve the issue.
I recently installed a copy of discourse on aws. The installation is working however when I register a new account I don’t receive the email. When I check the logs I receive the following error.
Job exception: hostname "smtp.papertrail-ai.com" does not match the server certificate
Did you set up a DNS alias for the mail server? The subject name on its certificate is *.flk1.host-h.net. TLS needs a hostname match to make a secure connection, and the SMTP server doesn’t need to share the same domain as the sending domain, only to be authorized to send as it.