Using mailing list provide by mailman was a little bit ... user unfriendly so I try to find how can I get some nntp endpoint from a mailman mailing list in two different cases :
Case #1 : I got access to the mailman server configuration and can install some package to get a NNTP endpoint.
Case #2 : I don't have any access to the mailman configuration nor server. But I can install / deploy on an other server packages / script to provide some kind of "sync" with a nntp endpoint.
I make some research on Google and it seems there's dozen of script / package that post to a mailman mailing list from nntp but don't find and mailman to nntp solutions.
Mailman 2.0 has support for bi-directional NNTP gateway.
Check Mail-to-News and News-to-Mail gateway services option in administration WEB interface.