Migrating from Dovecot 1 to Dovecot 2

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.