[Mailman-Users] Mailman archive - archive date does not match the date the message was posted

There is an existing Mailman list with an archive which needs to be moved to a different server, however it seems that the archive is a bit messed up. I assume that the list was set up in 2006, but for some reason there is a 2002 archive, and all of the posts in there seem to have been posted in 2012. It's a public archive so I assume there's no harm in posting a link to it - https://secure.neap.net/pipermail/montrealers/. Is there some way to fix this?