1. Make a new blank mailman list

2. Set yourself as the admin and the only subscriber

3. Go into mailman's Defaults.py and change these settings:

Very important! If you don't change those, the archive threading will be
completely messed up.

4. Turn off respond_to_post_requests on the mailman general settings page for the list

Very important! If you don't turn this off, everyone will get lots of "your
message has been held" e-mails.

5. Find an e-mail program that has a 'bounce' or 'redirect with full headers' command

6. Start 'bounce'ing all messages related to the conversation to the new list's posting address

7. Verify that threading and attachments are being handled correctly in the archive

8. When you've finished creating the archive, subscribe everyone else to the list.