http://www.arnold-ont.ca/os2/os2_user_archive.html
This includes most of the posts in digest form starting in October 1999 and going through to December 2000. After that everything is available on yahoo groups. The site isn't searchable at the moment, but at least the
posts are available.
If anyone has any more of the digests that aren't on the site I would appreciate receiving a copy for inclusion.
Source: