It would be convenient for many users to have access to the contents of their File Store from a mail client (Thunderbird, Outlook, etc.), as well as via the Web Mail interface. For example: I use the Web Mail interface exclusively when I am work, and I often upload files to my File Store from there. Later, when I get home, I use a mail client (Thunderbird, in my case). Call it a brain fart if you must, but only then do I remember -- oh yeah, I have to use Web Mail to get there. Duh.
How it could work:
Upon successful upload of a file, the AMS program would also create a small, simple 'mail message' in the account, both from and to the given user, in a 'File Store' folder -- a folder managed much the same as other 'permanent' folders, such as inbox, sent, etc. The File Store items would be shown as attachments. The complication would be in the AMS program, where special attachment-type code might be required to avoid duplication of the File Store items and double-dipping the user's storage allocation.
Some might think this defeatist; after all, we use the very cool File Store to avoid sending mail to ourselves as a way of transferring data. But the point is to allow access to those files from a mail client, rather than a browser. The above method would accomplish this without the user having to actually send the mail to themselves.
Just a thought.