That file appears to be a binary file?  By itself it isn't enough to reproduce the problem.  Can you provide a complete script as well as the email message you are parsing that demonstrates the problem?

By "looks like any other eml file", are you including the MIME headers associated with the part?  Because it is the MIME headers that contain the information you say is missing.  Mostly likely, outlook is not supplying that information for these transformed eml files.  If you can supply a copy of the actual email message you are parsing, we should be able to confirm that.