I have a firebox 750e that keeps deleting this particular pdf. I can get other pdfs so it is not a file type issue. Additionally the sender is known and trusted. Here is the message:
The WatchGuard Firebox which protects your network detected a message which may not be safe.
Cause : The message content may not be safe.
Content type : application
File name : Rimrock Resolutions.PDF
Virus status : No information.
Action : The Firebox deleted Rimrock Resolutions.PDF.
Your network administrator can not restore this attachment.