One other problem is that, for the most part, the folders are only available when the user is logged into the particular PC on which the folder is located. Thus when you are not in your office, you can still read your Exchange email (simply by logging in on another PC), but cannot access your Personal Folders.

An Obvious Solution presents itself -- put the folder on a network share that you "own". This solves the "visibility" problem (assuming that the share gets mounted as part of the logon process), solves the backup problem (assuming that the network share is backed up centrally), and solves the "access" problem (as you can "see" it from anywhere in the network).

Under our "storage" model, data are rarely entered into the folders, meaning it is even more unlikely that data will come in from two different "directions". On the other hand, I would not expect that multiple "read" requests of the .PST file would lead to a compromise in the structure of the .PST.

In addition to this "single user" scenario, where keeping the Personal Folder on a share makes it much more accessible to the user (in principle, the user can even access these folders from home!), we utilize a number of "shared mailboxes" for common tasks.

An example
For example, we run a small journal with its own mailbox, journal@school.edu. The two editors and the administrative assistant all have full access privileges to this mailbox, and all have this mailbox added to their Outlook folder list. Because multiple people are sharing the mailbox, they also need to be able to share the "storage folders".

Given that the business of the journal is accepting manuscripts (with figures!) and sending them to reviewers, a simple Exchange mailbox of even "enhanced" size (40MB) can fill up quickly, hence the absolute requirement for additional mail storage.

To accommodate multiple users, a "share" belonging to those users seems to be the natural and logical place to save the resulting .PST files. It neatly solves the "visibility", "backup", and "access" problems, even here, where "access" means "by different users from different computers".

We have been using this scheme quite successfully for several years, without any failures. Indeed, I was shocked to learn (as narrated at the top of this article) that such LAN storage of .PST files was "unsupported" and not recommended. We did notice that when using shared folders, only one user at a time can open the .PST file. Given the danger in having two people trying to update the same .PST over the network, this is probably a "good thing", and one to which we have adapted our behavior (usually, if an editor needs to use the shared folder and can't get in, the other two users are simply asked to exit Outlook, and re-open it, allowing the editor to "grab" the folder for exclusive use).