Have to make a backup

Found at: uninformativ.de:70/twitpher/2012-09/2012-09-18.txt

  Have  to make a backup of e-mails in MS Outlook. That backup has to be
  readable by everything, so, ideally, a Maildir would be lovely.
  Now what?
  MS Outlook can only export  mails  to  "PST"  (a  useless  proprietary
  format) or CSV. Seriously, CSV.
  Not that we have standards like RFC822 or MIME... No, let's use CSV.
  Oh, dear.