imap/pop proxy

Hi all first time user as dovecot imap/pop3 proxy.

As i'm migrating some mailboxes to a new server, i would like to move a couple at once, not everything (more than 10k).

The quickest way would be to setup the current (and old) dovecot server as pop3/imap server AND proxy.

I'm thinking to start returning proxy_maybe in the password DB query, pointing to the mailbox server. If the mailbox server is migrated to the new one, proxy_maybe will point to the remote server, if the mailbox is still on the old server, proxy_maybe will point to localhost.

Is this enough ? Password auth should be done on the "remote" server and not by the proxy itself.

Ideas ?