Ask Bjorn Hansen is my hero. :-)
A few months ago, I tried to create mailbox archives of some Perl mailing lists on perl.org. Unfortunately, ezmlm does not save the references and message id headers when it stores messages for digests. Also, many messages were missing from some of the larger mailing lists (e.g. beginners@perl.org). This lost information inhibited threading in my mailer (mutt).
Now that nntp.perl.org is operational, all of the posts are available *with* the references and message ids! Building up archival mailboxes is as simple as newsfetch nntp.perl.org.
Thanks again, Ask.