They are returned to a central mailbox and currently I have a macro that
saves the files to a folder dependent on filename (I can get that one
easily).  However, users keep changing the filenames (as people are inclined
to do) so I end up going through a large proportion of them each time (around
10% of 500 every other day).

The Subject I'm talking about is held within the File properties of an excel
file that you see by selecting properties from Explorer or within Excel
itself.  I know how to retrieve this when the file is open but I don't want
to open the file from the email (due to server delays it would take far too
long) and then retrieve it.

I was hoping there would be some way to retrieve this via Outlook without
opening it.  This would mean I could add the correct filename into the
subject of the Excel sheet when it's generated and then I wouldn't have to
worry about people changing them.