You are trying to send an email to be encrypted for delivery, but Track and Trace is showing those emails as "Not Delivered".
The reason that encrypted emails show up in the track and trace as "Not Delivered" is because of the redirect action that is taken in the encryption policy. Track and Trace is reporting the email as not delivered because it was not sent to the original recipient but instead directed to the encryption service which will then send it to the intended recipient.
When an email is redirected it reports as "Not Delivered" because the email did not go directly to the original recipient.