Seriously no one? This will take only 1 minute.
I've checked secondary mail server where no gateway is being used (free version used only for support mailboxes for one domain) and there Ham\Type3 messages are from year 2013. As far as I can see in this KB article:
http://portal.smartertools.com/kb/a2793/understanding-the-roles-of-the-ham-and-spam-folders-in-bayesian-filtering.aspx?KBSearchID=681425
this directories should contain recent random messages and there is no information if this messages are being stored always or maybe under certain conditions.