Error: Could not find the encrypted attachment for this message
When troubleshooting the Outlook Add-in it is good to note any error messages. The error "Could not find the encrypted attachment for this message" occurs when attempting to use a version of the Outlook Add-in that is no longer supported. You can find more about the Protected Trust Outlook Add-in versions here.
Hint: Remember you can always go to https://app.protectedtrust.com and sign in to the web app to view protected messages in your Inbox or Compose and Send a protected message.