Is there a 3rd party (or Microsoft) utility that provides all or part of this
functionality?

Server-side app/event sink that can replace attachments with hyperlinks and
store those attachments outside of the Exchange system, i.e. to a share on
our file server. Additionally, it would be great if the app were smart enough
to keep only one copy of the attachment no matter how many users it was sent
to. And it should be able to replace the hyperlink with a copy of the
original attachment for forwards and replies that go to recipients outside
our domain. If it were really smart, it might even index the attachments and
make them searchable via Outlook or the Web for our users.

We plan to use Outlook 2003's auto-archive features to manage our edb sizes.
If there is an app that consolidates the above, centralize policies and can
auto-number PSTs, that would be wonderful...