Namecheap Private Email (SMTP) からセルフホスト Discourse へのメール送信に問題があります

You should use a transaction mail serive like Mailgun, Brevo or Amazon SES. That’s the optimal way to send emails from your forum.

See discourse/docs/INSTALL-email.md at main · discourse/discourse · GitHub

You may also want to check out:

「いいね!」 1