imap dovecot sendmail mailbox maildir

The following tool helped me a great deal in migrating inboxes to a new server : http://perfectmaildir.home-dn.net/
 
What I did was setup the user accounts on the new server, and then copied the users' mailbox files from /var/spool/mail on the old box to a temp folder on the new box.
 
After using

sudo perl -MCPAN - e shell
> install Date::Parse

to setup some pre-reqs for the script, it ran perfectly!