The following behavior is what we are experiencing when using Office
2003 against WSS/SPS2003. Would someone confirm that this is the
proper results (i.e. by design)? When in Outlook 2003 and attaching
a document you have the option to use a document workspace to share
the document. We experience this:

Scenario 1 -
If the URL uses the NetBIOS name of the server, the document
workspace is created just fine. Nothing need to be trusted (presumed
to be in the Intranet Zone).

Scenario 2 -
If the URL uses the FQDN of the server and the server's FQDN is in
the Trusted Sites Zone then the workspace is created just fine.

Scenario 3 -
If the URL uses the FQDN of the server and the server's FQDN is NOT
in the Trusted Sites Zone then creation fails with this message:
"Shared attachments are not available for this location. You may not
have permission to access the location, it may not be a trusted site,
or it may be unavailable."

In the above scenarios the URL is a reference to "MySite" by either
http://netbios/personal/username or http://fqdn/personal/username
depending on the situation as shown above. A search on
Google/GoogleGroups returns few hits the most similar being this
article/FAQ:
wss.collutions.com/Lists/FAQ/Comments.aspx?ID=205