I usually use Outlook Express for this as it have integrated support for
newsgroup, something that Outlook (the one that come with Office, without
the Express word) doesn't have but usually Outlook is able to open Outlook
Express when necessary for dealing with newsgroup.
If you don't have Outlook Express installed on your machine, than it is
concevable that Outlook will be unable to send message for newsgroup.
Try clicking the following link or enter it in the IE address bar to see if
Outlook will have a reaction:
news://news.microsoft.com/microsoft.public.access.adp.sqlserver
S. L.