Thank you the answer.
I have an old server old ISP control software it has existing domains and e-mail boxes width e-mails in Courier maildir format.
I have a new server with ISPManager ISP control software with Dovecot.
For example:
I have on the old server example.com domain and
user@example.com e-mail box with e-mails stored in Courier maildir format.
I create also on the new server the example.com domain and
user@example.com e-mail box.
Then I will copy
user@example.com messages from old server to the new server for user
user@example.com maildir directory?
Is this a good solution to move e-mails from old to the new server?
Other: The Courier maildir format compatible with Dovecot maildir format?
Thanks!