I think that there should be an option allowing to archive mails according to date of reception of the posts by mailman, and not date set by user who sends it. That would prevent dates from the future in the archive: 2006, 2011, 2013, 2024, which you can see in many lists, like for example mailman-users archive: http://mail.python.org/pipermail/mailman-users/

Regards Andy