well the release date will be (hopefully) monday! I'm just waiting for the last language translation.
To your problem:
When you use 8.5.2 I strongly recommend to use the EML viewer delivered with the client itself. That makes life much more easier.
The reason: depending on the structure of the original mail there may be problems displaying them in the File Navigator EML viewer. If you like you can drop me an eMail with such an "wrong displayed" mail at firstname.lastname@example.org. I'll take a look at it then.