Backing up e-mail with Qmail

Can someone point me in the right direction on how to backup pop e-mail with qmail automatically when an e-mail comes in for a duration of a month to restore at a later date if needed?

I know all of the individual emails are in /var/qmail/mailnames/domain/username/Maildir/new/ directory. But how do you back these up when they come in and retain them for a month or so?

Thank you in advance.