You have told Metabase to send email notifications, but:
Before any other troubleshooting, try sending a test email to isolate the problem.
Root cause: The host, port, email address, or password may have been set up incorrectly, or the email server’s host and port have been set up incorrectly.
Steps to take:
Root cause: Some email delivery services have very specific rules regarding valid “from” addresses, or have test modes that restrict delivery.
Steps to take:
Root cause: The message is being sent correctly, but isn’t being received (at least, not where you expect it to be).
Steps to take: