When you see this message it is because you are not an authorised recipient of the secure email, this could be for one of the following reasons:
The email address that the secure email was sent to is different to the email address that you are using to sign into your Switch account.
The secure email was forwarded to your email address, meaning that you were not the original recipient of the email.
To gain access to the package you need to request access from the author of the email. You will have the option to do this below where you are seeing the ‘Access Denied’ message; once the author has granted you access you will be notified via email.