I'd publish it as a subweb, maybe as a subweb within a subweb.
you could make a subweb called /newsletters and publish your newsletters
into it so that it acts as sort of an archive of newsletters by using the
FrontPage table of contents components on the index page of it. (you'd just
put your newsletters into folders within the subweb)
as for making a subweb:
on your local computer it's just like making any web and to publish just
type the address you want it to go to such as
http://example.com/mysubweb if
your extensions are set right you'll get a message on publishing to the
effect "no subweb exists at
http://example.com/mysubweb do you want
FrontPage to create a web at that location". chose yes and you're rolling.
HTH