You have to use a news server that carries that group. Like www.Giganews.com, or one hosted by your ISP.
The Microsoft Communities is a Microsoft news only server.
It's not that it is not possible. The problem you are having and I assume
you mean you cannot access the specific newsgroup, is that the group is not
on that particular server. The default server in Windows Mail is the
Microsoft server. You need to check with your ISP, your Internet Service
Provider to see if they have a Usenet server and for instructions as to the
name of the server and how to set it up. Once you set it up, you will
download a list of available newsgroups on that server and if the group(s)
you've specified are on that server, you will be able to access those
groups.