Migrating from Dovecot 1 to Dovecot 2

[Dovecot list]

Hello.
I try to migrate about 200G of mails from one server to another.
On the old i have Dovecot1 with Maildirs (without master pass etc.), on the
new one i setup dovecot2 with mdbox. I need now to migrate (partialy, not
all at once) mails from one to another.
I can't find any solution that i can use? I dont have master password, and
i want to mikgrate all mailaccont each other. Can anyone use me a working
config for this ? Best will be that migratet dont want to be downloaded by
mail client one more time.
Thanks for any help.
Best regards.