I released a quarantined email from the Network Box, but instead of receiving the email, I only got an email from Network Box warning me about the content of the email. Where is my email?
When the message is released by the Network Box, it is sent as an attachment to the email to which you are referring.
If you are unable to see the email then this Microsoft Knowledge Base Article may help to explain why.
A quick way to test if this problem is affecting you, is to open your mailbox in Outlook Web Access where you should be able to see the original email as an attachment.