[Dovecot] Problems Converting Maildir to mdbox

Hello,

I would like to convert all users mail from maildir to mdbox. My Dovecot version is 2.0.1, converted from 1.2.13 but config was rewritten from scratch.

http://wiki2.dovecot.org/Migration/MailFormat says following: maildir -> mdbox migration. Set mail_location=mdbox:~/mdbox and run doveadm convert -u username maildir:~/Maildir

but doveadm does not know a command like "convert". Is there a _working_ way to convert maildir to mdbox ? How to do that with all Dovecot mail users (about 10000) ?

Christian